CPS20.241-D1
24V, 20A, DC/DC CONVERTER

C-Series

DC/DC CONVERTER
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88-360Vdc Wide-range Input
Width only 65mm
Efficiency up to 94.6%
ATEX and IECEx Approved
Excellent Partial Load Efficiency
20% Output Power Reserves
Safe HiccupPLUS Overload Mode
Easy Fuse Tripping due to High Overload Current(typ. 80A for 15ms)
Minimal Inrush Current Surge
Full Power Between -25°C and +60°C
DC-OK Relay Contact
Reverse Input Polarity Protected
Current Sharing Feature for Parallel Use
3 Year Warranty

GENERAL DESCRIPTIONSHORT-FORM DATAThe Dimension C-Series are cost optimized power
supplies and DC/DC converters without compromisingquality, reliability and performance. The C-Series is partof the DIMENSION power supply family. The mostoutstanding features of CPS20.241-D1 are the wide DCinput range, high efficiency, electronic inrush current
limitation, wide operational temperature range. The
small size is achieved by a synchronous rectification andfurther technological design details.

Output voltage
Adjustment range
Output current

The C-Series includes all the essential basic functions.
The devices have a power reserve of 20% included,
which may even be used continuously at temperatures
up to +45°C. Additionally, the CPS20.241-D1 can deliver
about 4 times the nominal output current for 15ms
which helps to trip fuses on faulty output branches.
High immunity to transients and power surges as well as
low electromagnetic emission, a DC-OK relay contact
and a large international approval package for a variety
of applications makes this unit suitable for nearly every
situation.

ORDER NUMBERS

DC 24V24 - 28V
20A
at 24V, amb <60°C
24A
at 24V, amb <45°C
17.1A
at 28V, amb <60°C
20.6A
at 28V, amb <45°C
Output power
480W
ambient <60°C
576W
ambient <45°C
Output ripple< 50mVpp
20Hz to 20MHz
AC Input voltage
DC Input voltage
DC 110-300V± 20%
DC Input current
4.68 / 1.69A
at 110 / 300Vdc
Inrush current
typ. 6 / 4A peak at 110 / 300Vdc
Efficiency
93.1 / 94.6%
at 110 / 300Vdc
Losses35.6 / 27.4W
at 110 / 300Vdc
Temperature range -25°C to +70°C operational
Derating
12W/°C+60 to +70°C
Hold-up time
typ. 26 / 26ms
at 110 / 300Vdc
Dimensions
65x124x127mm WxHxD
Weight940g 2.1lb

MARKINGS

DC/DC converter CPS20.241-D1 24-28V Standard unit
Accessory

ZM2.WALL
ZM13.SIDE
YR40.242
YR40.245

Wall mount bracket
Side mount bracket
Redundancy module
Redundancy module

IND. CONT. EQ.

UL 60950-1

UL 508IECEx
Class I Div 2

ATEX

II 3G Ex nA nC II T3 Gc

Apr. 2014 / Rev. 1.3 DS-CPS20.241-D1-EN
All parameters are specified at 24V, 20A, 300Vdc, 25°C ambient and after a 5 minutes run-in time unless otherwise noted.
www.pulspower.com Phone +49 89 9278 0

EMC, LVD, RoHS

Germany

1/25

CPS20.241-D1
24V, 20A, DC/DC CONVERTER

C-Series

INDEX
Page
1. Intended Use .......................................................3
2. Installation Requirements...................................3
3. AC-Input...............................................................4
4. DC-Input...............................................................4
5. Input Inrush Current ...........................................5
6. Output .................................................................6
7. Hold-up Time.......................................................8
8. DC-OK Relay Contact ..........................................8
9. Efficiency and Power Losses................................910. Lifetime Expectancy and MTBF.........................10
11. Functional Diagram...........................................10
12. Terminals and Wiring........................................11
13. Front Side and User Elements...........................12
14. EMC....................................................................13
15. Environment ......................................................14
16. Protection Features ...........................................15
17. Safety Features ..................................................15
18. Dielectric Strength ............................................16
19. Approvals...........................................................16Page
20. Physical Dimensions and Weight ..................... 17
21. Accessories ........................................................ 18
21.1. ZM2.WALL - Wall Mounting Bracket.......18
21.2. ZM13.SIDE - Side Mounting Bracket........18
21.3. Redundancy Modules ...............................19
22. Application Notes............................................. 20
22.1. Peak Current Capability ...........................20
22.2. Inductive and Capacitive Loads................21
22.3. External Input Protection.........................21
22.4. Output Circuit Breakers............................21
22.5. Parallel Use to Increase Output Power....22
22.6. Parallel Use for Redundancy ....................22
22.7. Series Operation .......................................23
22.8. Back-feeding Loads ..................................23
22.9. Charging of Batteries ...............................24
22.10. Use in a Tightly Sealed Enclosure ............24
22.11. Mounting Orientations ............................25

The information presented in this document is believed to be accurate and reliable and may change without notice.
No part of this document may be reproduced or utilized in any form without permission in writing from the publisher.

TERMINOLOGY AND ABREVIATIONSPE andsymbolPE is the abbreviation for Protective Earth and has the same meaning as the symbol.

Earth, Ground

This document uses the term “earth” which is the same as the U.S. term “ground”.

T.b.d.

To be defined, value or description will follow later.

DC 300V

A figure displayed with the AC or DC before the value represents a nominal voltage withstandard tolerances (usually ±15%) included.
E.g.: DC 12V describes a 12V battery disregarding whether it is full (13.7V) or flat (10V)

300VdcA figure with the unit (Vdc) at the end is a momentary figure without any additional
tolerances included.

may

A key word indicating flexibility of choice with no implied preference.

shall

A key word indicating a mandatory requirement.

shouldA key word indicating flexibility of choice with a strongly preferred implementation.

Apr. 2014 / Rev. 1.3 DS-CPS20.241-D1-EN
All parameters are specified at 24V, 20A, 300Vdc, 25°C ambient and after a 5 minutes run-in time unless otherwise noted.
www.pulspower.com Phone +49 89 9278 0Germany

2/25

CPS20.241-D1
24V, 20A, DC/DC CONVERTER

C-Series

1. INTENDED USEThis device is designed for installation in an enclosure and is intended for the general professional use such as inindustrial control, office, communication, and instrumentation equipment.
Do not use this DC/DC converter in equipment, where malfunction may cause severe personal injury or threaten
human life.
This device is designed for use in hazardous, non-hazardous, ordinary or unclassified locations.

2. INSTALLATION REQUIREMENTS
This device may only be installed and put into operation by qualified personnel.
This device does not contain serviceable parts. The tripping of an internal fuse is caused by an internal defect.
If damage or malfunction should occur during installation or operation, immediately turn power off and send unit to
the factory for inspection.
Mount the unit on a DIN-rail so that the terminals are located on the bottom of the unit. For other mounting
orientations see de-rating requirements in this document. See chapter 24.13.
This device is designed for convection cooling and does not require an external fan. Do not obstruct airflow and do
not cover ventilation grid (e.g. cable conduits) by more than 15%!
Keep the following installation clearances: 40mm on top, 20mm on the bottom, 5mm on the left and right sides arerecommended when the device is loaded permanently with more than 50% of the rated power. Increase this clearance
to 15mm in case the adjacent device is a heat source (e.g. another power supply).
A disconnecting means shall be provided for the output of the power supplies when used in applications according to
CSA C22.2 No 107.1-01.

WARNING

Risk of electrical shock, fire, personal injury or death.

- Do not use the DC/DC converter without proper grounding (Protective Earth). Use the terminal on the input blockfor earth connection and not one of the screws on the housing.
- Turn power off before working on the device. Protect against inadvertent re-powering.
- Make sure that the wiring is correct by following all local and national codes.
- Do not modify or repair the unit.
- Do not open the unit as high voltages are present inside.
- Use caution to prevent any foreign objects from entering the housing.
- Do not use in wet locations or in areas where moisture or condensation can be expected.
- Do not touch during power-on, and immediately after power-off. Hot surfaces may cause burns.
Notes for use in hazardous location areas:
The power supply is suitable for use in Class I Division 2 Groups A, B, C, D locations and for use in Group II Category 3(Zone 2) environments and are evaluated according to EN 60079-0:2012 and EN 60079-15:2010.
WARNING EXPLOSION HAZARDS!
Substitution of components may impair suitability for this environment. Do not disconnect the unit or operate thevoltage adjustment or S/P jumper unless power has been switched off or the area is known to be non-hazardous.

Apr. 2014 / Rev. 1.3 DS-CPS20.241-D1-EN
All parameters are specified at 24V, 20A, 300Vdc, 25°C ambient and after a 5 minutes run-in time unless otherwise noted.
www.pulspower.com Phone +49 89 9278 0Germany

3/25

CPS20.241-D1
24V, 20A, DC/DC CONVERTER

C-Series

3. AC-INPUT
Do not operate this DC/DC converter with AC-input voltage. Use the CPS20.241 unit instead.

4. DC-INPUT
Use a battery or a similar DC source. A supply from the intermediate DC-bus of a frequency converter is notrecommended and can cause a malfunction or damage the unit.

Allowed voltage between input
to earth (ground)
Slew rate for voltage between
input to earth (ground)
Allowed input ripple voltage

nom.
min.
min.

DC 110-300V
88-360Vdc
88-100Vdc

min.
max.

360-425Vdc
360Vdcpeak value, allowed for transientsmax.

± 600V
1000V/μs
50Vpp
15Vpp
85Vdc
37Vdc
50Vdc
69Vdc

50Hz –10kHz
10kHz – 50kHz
steady-state value, see Fig. 4-1
steady-state value at 5A load, see Fig. 4-1
steady-state value at 10A load, see Fig. 4-1
steady-state value at 20A load, see Fig. 4-1

max.

Turn-on voltage
Shut-down voltage

typ.
typ.
typ.
typ.

Input current
Start-up delay
Rise timeTurn-on overshoot

typ.
typ.
typ.

DC 110V
4.68A
1100ms85ms

DC 300V
1.69A
830ms
85ms

typ.

150ms

150ms

max.

200mV

200mV

Fig. 4-1 Input voltage range

Rated
input range

max.
500ms

Input
Voltage

OutputVoltageVIN
88V

at 24V, 20A, see Fig. 4-3
see Fig. 4-2
at 24V, 20A const. current load, 0mF
load capacitance, see Fig. 4-2
at 24V, 20A const. current load, 20mF
load capacitance, see Fig. 4-2
see Fig. 4-2

Fig. 4-2 Turn-on behavior, definitions

Turn-onShut-down

POUT

short term or with output derating (1%/V) or with
reduced ambient temperature, see also Fig. 15-1,
no damage between 0 and 88Vdc
short term, < 500ms
continuous, IEC 62103- 5%Start-up
delay

Rise
Time

OvershootDC input
DC input range

360V 425Vdc

Apr. 2014 / Rev. 1.3 DS-CPS20.241-D1-EN
All parameters are specified at 24V, 20A, 300Vdc, 25°C ambient and after a 5 minutes run-in time unless otherwise noted.
www.pulspower.com Phone +49 89 9278 0Germany

4/25

CPS20.241-D1
24V, 20A, DC/DC CONVERTER

C-Series

Fig. 4-3 Input current vs. output load at 24V
Input Current, typ.

6A
5

110

4

c
Vd

3
300Vdc2
1
Output Current

0
2

4

6

8 10 12 14 16 18 20 22 24A

5. INPUT INRUSH CURRENT
An active inrush limitation circuit limits the input inrush current after turn-on of the input voltage and after short
input voltage interruptions.
The charging current into EMI suppression capacitors is disregarded in the first microseconds after switch-on.

Inrush current*)

max.
typ.
max.
typ.

Inrush energy*)
Inrush delay*)

DC 110V
13Apeak
6Apeak
1A2s
1185msDC 300V
10Apeak
4Apeak
1A2s
915ms

temperature independent
temperature independent
temperature independent
start-up delay plus rise time

Mains interruptions > 500ms

Fig. 5-1 Typical input inrush current
behaviour at nominal load and 25°C ambient

Input Current
2A / DIV

Input

300Vdc24Vdc

Output
200mS/DIV

Apr. 2014 / Rev. 1.3 DS-CPS20.241-D1-EN
All parameters are specified at 24V, 20A, 300Vdc, 25°C ambient and after a 5 minutes run-in time unless otherwise noted.
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CPS20.241-D1
24V, 20A, DC/DC CONVERTER

C-Series

6. OUTPUT
Output voltage
Adjustment range

nom.
min.
max.
typ.
typ.
typ.
max.
max.

24V
24-28V
30V****)
24.1V
24.1V
25.1V
10mV
100mV

typ.

1000mV

Ripple and noise voltage
Output current

max.
nom.
nom.
nom.
nom.
typ.

70mVpp
20A
24A*)
17.1A
20.6A*)
80A

Output power

nom.
nom.

min.
max.
max.

480W
576W*)
cont. current
HiccupPLUS mode**)35A***)
45A***)
15A***)

min.
typ.
typ.

70A
100A
7 000μF

Factory settings

Line regulation
Load regulation

Overload behaviour
Short-circuit current

Output capacitance
*)

**)

***)
****)

guaranteed
at clockwise end position of potentiometer±0.2%, at full load, cold unit, in “single use” mode
±0.2%, at full load, cold unit, in “parallel use” modeat no load, cold unit, in “parallel use” mode
88-370Vdc
in “single use” mode: static value, 0A Æ 20A;
see Fig. 6-1
in “parallel use” mode: static value, 0A Æ 20A,
see Fig. 6-2
20Hz to 20MHz, 50Ohm
at 24V, ambient temperature <60°C, see Fig. 6-1
at 24V, ambient temperature <45°C, see Fig. 6-1
at 28V, ambient temperature <60°C, see Fig. 6-1
at 28V, ambient temperature <45°C, see Fig. 6-1
up to 15ms, output voltage stays above 20V, see Fig.
6-4. This peak current is available once every fiveseconds. See chapter 22.1 for more peak current
measurements.
continuously available
Power Boost®*)output voltage > 13Vdc, see Fig. 6-1
output voltage < 13Vdc, see Fig. 6-1
load impedance <10mOhm, see Fig. 6-3
load impedance <10mOhm, see Fig. 6-3
average (R.M.S.) current, load impedance 50mOhm,
see Fig. 6-3< 15ms, load impedance <10mOhm, see Fig. 6-4< 15ms, load impedance <10mOhm, see Fig. 6-4
included inside the DC/DC converter

Power Boost
This power/ current is continuously allowed up to an ambient temperature of 45°C.
Above 45°C, do not use this power/ current longer than a duty cycle of 10% and/ or not longer than 1 minute every 10 minutes.
HiccupPLUS ModeAt heavy overloads (when output voltage falls below 13V), the DC/DC converter delivers continuous output current for 2s. After this,the output is switched off for approx. 18s before a new start attempt is automatically performed. This cycle is repeated as long as theoverload exists. If the overload has been cleared, the device will operate normally. See Fig. 6-3.
Discharge current of output capacitors is not included.
This is the maximum output voltage which can occur at the clockwise end position of the potentiometer due to tolerances. It is notguaranteed value which can be achieved. The typical value is about 28.5V (in “single use” mode).

Apr. 2014 / Rev. 1.3 DS-CPS20.241-D1-EN
All parameters are specified at 24V, 20A, 300Vdc, 25°C ambient and after a 5 minutes run-in time unless otherwise noted.
www.pulspower.com Phone +49 89 9278 0Germany

6/25

CPS20.241-D1
24V, 20A, DC/DC CONVERTER

C-Series

Fig. 6-2 Output voltage in “parallel use”
mode, typ.

Fig. 6-1 Output voltage vs. output current,
typ.
Output Voltage (Single Use, typ.)

28V
Factory
setting16

Adjustment
Range

29V

Continuous
current

24
20

Output Voltage (Parallel Use, typ.)Adjustment
Range

28V
27V
26V
25V

12
8
4
0

23V
22V

Output Current

0

5

10

15

20

25

30

Factory
setting

24V

Hiccupmode

35 40A

Output Current

40

Fig. 6-3 Short-circuit on output, HiccupPLUS mode, typ.

8

12

16

20

24A

Fig. 6-4 Dynamic overcurrent capability, typ.
Output Voltage (dynamic behavior, < 15ms)

28V

OutputCurrent
Normaloperation

Normaloperation

Short -circuit

42A

24
20

Adjustment
Range

16
12
t

0
2s

18s

2s

18s

2s

18s

8
4
0

Output Current

0 10 20 30 40 50 60 70 80 90 100A

Apr. 2014 / Rev. 1.3 DS-CPS20.241-D1-EN
All parameters are specified at 24V, 20A, 300Vdc, 25°C ambient and after a 5 minutes run-in time unless otherwise noted.
www.pulspower.com Phone +49 89 9278 0Germany

7/25

CPS20.241-D1
24V, 20A, DC/DC CONVERTER

C-Series

7. HOLD-UP TIME
The internal capacitor, which supplies the energy for the hold-up time is isolated by a diode to the input voltage. A
short on the input line does not discharge the internal hold-up capacitor.

Hold-up TimeDC 110V
65ms
54ms
26ms
21ms

typ.
min.
typ.
min.

Fig. 7-1 Hold-up time vs. input voltage

DC 300V
65ms
54ms
26ms
21ms

at 24V, 10A, see Fig. 7-1
at 24V, 10A, see Fig. 7-1
at 24V, 20A, see Fig. 7-1
at 24V, 20A, see Fig. 7-1

Fig. 7-2 Shut-down behavior, definitions

Hold-up Time

80ms
70
60
50
40
30
20
10
0
120

24V, 10A, typ.

Input
Voltage

24V, 10A, min.

24V, 20A, typ.
24V, 20A, min.

- 5%

OutputVoltage
Hold-up Time

Input Voltage

180

240

300

360Vdc8. DC-OK RELAY CONTACT
This feature monitors the output voltage, which is produced by the DC/DC converter itself. It is independent of a backfed voltage from a unit connected in parallel to the DC/DC converter output.
Contact closes
Contact opens

As soon as the output voltage reaches 90% of the adjusted output voltage level.
As soon as the output voltage dips more than 10% below the adjusted output voltage.
Short dips will be extended to a signal length of 100ms. Dips shorter than 1ms will be ignored.
max.
60Vdc 0.3A, 30Vdc 1A, 30Vac 0.5A
resistive loadmin.
1mA at 5Vdc
min. permissible load
See dielectric strength table in section 18.

Contact ratings
Isolation voltage

Fig. 8-1 DC-ok relay contact behavior
VOUT = VADJ
10%

<
1ms

open

closed>1ms

0.9* VADJ

100ms

open

closedApr. 2014 / Rev. 1.3 DS-CPS20.241-D1-EN
All parameters are specified at 24V, 20A, 300Vdc, 25°C ambient and after a 5 minutes run-in time unless otherwise noted.
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CPS20.241-D1
24V, 20A, DC/DC CONVERTER

C-Series

9. EFFICIENCY AND POWER LOSSES
Efficiency
Average efficiency*)
Power losses

*)

typ.
typ.
typ.

DC 110V
93.1%
93.0%
91.8%

DC 300V
94.6%
94.4%
93.4%

typ.
typ.
typ.
typ.

7.6W
18.6W
35.6W
42.9W

2.7W
15.8W
27.4W
34.2W

at 24V, 20A
at 24V, 24A (Power Boost)
25% at 5A, 25% at 10A,
25% at 15A. 25% at 20A
at 24V, 0A
at 24V, 10A
at 24V, 20A
at 24V, 24A (Power Boost)

The average efficiency is an assumption for a typical application where the DC/DC converter is loaded with 25% of the nominal load for
25% of the time, 50% of the nominal load for another 25% of the time, 75% of the nominal load for another 25% of the time and with
100% of the nominal load for the rest of the time.

Fig. 9-1 Efficiency vs. output current at 24V,
typFig. 9-2 Losses vs. output current at 24V, typ.

Efficiency

Power Losses

96%
95
94
93
92
91
90
89
88

40W
35
30
25
20
15
10
5
0

b
a
a) 110Vdcb) 300Vdc
Output Current

4

6

8 10 12 14 16 18 20 22 24Aaba) 110Vdcb) 300Vdc
Output Current

0 2 4 6 8 10 12 14 16 18 20 22 24A

Fig. 9-3 Efficiency vs. input voltage at 24V,
20A, typ.

Fig. 9-4 Losses vs. input voltage at 24V, 20A,
typ.

Efficiency

Power Losses

96%

40W

95

35

94

30

93

25

92

20
15

91
Input Voltage

90
80

140

200

260

Input Voltage

10

320

380Vdc

80

140

200

260

320

380VdcApr. 2014 / Rev. 1.3 DS-CPS20.241-D1-EN
All parameters are specified at 24V, 20A, 300Vdc, 25°C ambient and after a 5 minutes run-in time unless otherwise noted.
www.pulspower.com Phone +49 89 9278 0Germany

9/25

CPS20.241-D1
24V, 20A, DC/DC CONVERTER

C-Series

10. LIFETIME EXPECTANCY AND MTBF
Lifetime expectancy*)

MTBF**) SN 29500, IEC 61709
MTBF**) MIL HDBK 217F

DC 110V
169 000h*)
478 000h*)
81 000h
228 000h*)
48 000h
136 000h*)
468 000h
770 000h
254 000h

DC 300V
194 000h*)
549 000h*)
98 000h
279 000h*)
56 000h
158 000h*)
537 000h
882 000h
290 000h

355 000h

395 000h

56 000h64 000h75 000h86 000hat 24V, 10A and 40°C
at 24V, 10A and 25°C
at 24V, 20A and 40°C
at 24V, 20A and 25°C
at 24V, 24A and 40°C
at 24V, 24A and 25°C
at 24V, 20A and 40°C
at 24V, 20A and 25°C
at 24V, 20A and 40°C;
Ground Benign GB40
at 24V, 20A and 25°C;
Ground Benign GB25
at 24V, 20A and 40°C;
Ground Fixed GF40
at 24V, 20A and 25°C;
Ground Fixed GF25*)

The Lifetime expectancy shown in the table indicates the minimum operating hours (service life) and is determined by the lifetime
expectancy of the built-in electrolytic capacitors. Lifetime expectancy is specified in operational hours and is calculated according to thecapacitor’s manufacturer specification. The manufacturer of the electrolytic capacitors only guarantees a maximum life of up to 15 years(131 400h). Any number exceeding this value is a calculated theoretical lifetime which can be used to compare devices.
**) MTBF stands for Mean Time Between Failure, which is calculated according to statistical device failures, and indicates reliability of adevice. It is the statistical representation of the likelihood of a unit to fail and does not necessarily represent the life of a product.
The MTBF figure is a statistical representation of the likelihood of a device to fail. A MTBF figure of e.g. 1 000 000h means thatstatistically one unit will fail every 100 hours if 10 000 units are installed in the field. However, it can not be determined if the failed unit
has been running for 50 000h or only for 100h.

11. FUNCTIONAL DIAGRAM
Fig. 11-1 Functional diagram+-

Input Fuse
Input Filter
Active Inrush Limiter
Reverse Polarity
Protection

Boost
ConverterPower
Converter

OutputFilterOutputVoltage
Regulator
Temperature
Shutdown

OutputPower
Manager

OutputOverVoltage
Protection

OutputVoltage
Monitor++Single /Parallel

VOUT
DC-ok
LED

DC-ok
Relay

DC-ok
Contact

Apr. 2014 / Rev. 1.3 DS-CPS20.241-D1-EN
All parameters are specified at 24V, 20A, 300Vdc, 25°C ambient and after a 5 minutes run-in time unless otherwise noted.
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10/25

CPS20.241-D1
24V, 20A, DC/DC CONVERTER

C-Series

12. TERMINALS AND WIRING
The terminals are IP20 Finger safe constructed and suitable for field- and factory wiring.
Input and output
screw terminals
0.5-6mm2
0.5-4mm2
AWG20-10
2.8mm (including ferrules)
7mm / 0.28inch
3.5mm slotted or cross-head No 2
1Nm, 9lb.in

Type
Solid wire
Stranded wire
American Wire Gauge
Max. wire diameter
Wire stripping length
Screwdriver
Recommended tightening torque

DC-OK-Signal
spring-clamp terminals
0.15-1.5mm2
0.15-1.5mm2
AWG26-14
1.5mm (including ferrules)
7mm / 0.28inch
3.5mm slotted (to open the spring)
not applicable

Instructions:a) Use appropriate copper cables that are designed for minimum operating temperatures of:
60°C for ambient up to 45°C and
75°C for ambient up to 60°C minimum
90°C for ambient up to 70°C minimum.
b) Follow national installation codes and installation regulations!
c) Ensure that all strands of a stranded wire enter the terminal connection!
d) Do not use the unit without PE connection.
e) Unused terminal compartments should be securely tightened.
f) Ferrules are allowed.
Daisy chaining:
Daisy chaining (jumping from one DC/DC converter output to the next) is allowed as long as the average output
current through one terminal pin does not exceed 25A. If the current is higher, use a separate distribution terminal
block as shown in Fig. 12-2.
Fig. 12-1 Daisy chaining of outputs

Power
Supply+ + Output-

Fig. 12-2 Using distribution terminals

Distribution
Terminals

Power
Supply+ + --Output

Load
+

-

Power
SupplyPower
Supply

+ + -

+ + -

-

Output-OutputLoad+-max 25A!
continuous

Apr. 2014 / Rev. 1.3 DS-CPS20.241-D1-EN
All parameters are specified at 24V, 20A, 300Vdc, 25°C ambient and after a 5 minutes run-in time unless otherwise noted.
www.pulspower.com Phone +49 89 9278 0Germany

11/25

CPS20.241-D1
24V, 20A, DC/DC CONVERTER

C-Series

13. FRONT SIDE AND USER ELEMENTS
Fig. 13-1 Front sideA

Input Terminals (screw terminals)+
Positive input–
Negative (return) input
PE (Protective Earth) input

B

Output Terminals (screw terminals, two pins per pole)+
Positive output–
Negative (return) output

C

Output voltage potentiometer
Open the flap to adjust the output voltage. Factory set: 24.1V

D DC-OK LED (green)
On, when the output voltage is >90% of the adjusted output voltage
E

DC-OK Relay Contact (quick-connect spring-clamp terminals)
The DC-OK relay contact is synchronized with the DC-OK LED.
See chapter 8 for details.

F“Parallel Use” “Single Use” selector
Set jumper to “Parallel Use” when DC/DC converter are connected in parallel
to increase the output power. In order to achieve a sharing of the load
current between the individual DC/DC converter, the “parallel use”
regulates the output voltage in such a manner that the voltage at no load isapprox. 4% higher than at nominal load. See also chapter 22.5. A missing
jumper is equal to a “Single Use” mode.

Apr. 2014 / Rev. 1.3 DS-CPS20.241-D1-EN
All parameters are specified at 24V, 20A, 300Vdc, 25°C ambient and after a 5 minutes run-in time unless otherwise noted.
www.pulspower.com Phone +49 89 9278 0Germany

12/25

CPS20.241-D1
24V, 20A, DC/DC CONVERTER

C-Series

14. EMCThe DC/DC converter is suitable for applications in industrial environment as well as in residential, commercial andlight industry environment without any restrictions. A detailed EMC report is available on request.
EMC Immunity
Electrostatic discharge
Electromagnetic RF field
Fast transients (Burst)

Surge voltage on input
Surge voltage on output
Surge voltage on DC-OK
Conducted disturbanceAccording generic standards: EN 61000-6-1 and EN 61000-6-2
EN 61000-4-2
contact discharge
8kV
air discharge
15kV
EN 61000-4-3
80MHz-2.7GHz
20V/m
EN 61000-4-4
input lines
4kV
output lines
2kV
DC-OK signal (coupling clamp)
2kV
EN 61000-4-5+Æ2kV+ Æ PE, - Æ PE
4kV
EN 61000-4-5+Æ1kV+ / - Æ PE
2kV
EN 61000-4-5
DC-OK signal Æ PE
1kV
EN 61000-4-6
0.15-80MHz
20V

Criterion A
Criterion A
Criterion A
Criterion A
Criterion A
Criterion A
Criterion A
Criterion A
Criterion A
Criterion A
Criterion A
Criterion A

Criterions:
A: DC/DC converter shows normal operation behavior within the defined limits.
C: Temporary loss of function is possible. DC/DC converter may shut-down and restarts by itself. No damage or hazards for the DC/DC
converter will occur.

According generic standards: EN 61000-6-3 and EN 61000-6-4
EMC Emission
Conducted emission
CISPR 16-1-2, CISPR 16-2-1
limits for DC power port
input lines
according EN 61000-6-3 fulfilled
CISPR 16-1-2, CISPR 16-2-1
limits for DC power port
Conducted emission
according EN 61000-6-3 fulfilled
output lines*)
Radiated emission
EN 55011, EN 55022
Class B
This device complies with FCC Part 15 rules.
Operation is subjected to following two conditions: (1) this device may not cause harmful interference, and (2) thisdevice must accept any interference received, including interference that may cause undesired operation.
*)for information only, not mandatory for EN 61000-6-3

Switching Frequencies
Switching frequency 1
Switching frequency 2

The DC/DC converter has two converters with two different switching frequencies
included.
70kHz to 130kHz
PFC converter, input voltage and output power dependent
80kHz to 140kHz
Main converter, output power dependent

Apr. 2014 / Rev. 1.3 DS-CPS20.241-D1-EN
All parameters are specified at 24V, 20A, 300Vdc, 25°C ambient and after a 5 minutes run-in time unless otherwise noted.
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13/25

CPS20.241-D1
24V, 20A, DC/DC CONVERTER

C-Series

15. ENVIRONMENT
Operational temperature*)
Storage temperature
Output de-rating-25°C to +70°C (-13°F to 158°F)-40 to +85°C (-40°F to 185°F)
6.4W/°C
12W/°C
5 to 95% r.h.
2-17.8Hz: ±1.6mm; 17.8-500Hz: 2g***)2 hours / axis
30g 6ms, 20g 11ms***)3 bumps / direction, 18 bumps in total
0 to 2000m (0 to 6 560ft)
2000 to 6000m (6 560 to 20 000ft)

Humidity **)Vibration sinusoidal
Shock
Altitudereduce output power according Fig. 15-1
for storage and transportation
45°C to 60°C (113°F to 140°F)
60°C to 70°C (140°F to 158°F)
IEC 60068-2-30
IEC 60068-2-6
IEC 60068-2-27

without any restrictions
reduce output power or ambient temperature,
see Fig. 15-2
IEC 62103, EN 50178, overvoltage category II
30W/1000m or 5°C/1000m> 2000m (6500ft), see Fig. 15-2
III
IEC 62103, EN 50178, altitudes up to 2000m
II
altitudes from 2000m to 6000m
2
IEC 62103, EN 50178, not conductive
The unit does not release any silicone or other LABS-critical substances and is suitable foruse in paint shops.
At load currents below 2A some audible noise will be emitted from the DC/DC converter

Altitude de-rating
Over-voltage category
Degree of pollution
LABS compatibility
Audible noise*) Operational temperature is the same as the ambient temperature and is defined as the air temperature 2cm below the unit.
**) Do not energize while condensation is present***) Tested in combination with DIN-Rails according to EN 60715 with a height of 15mm and a thickness of 1.3mm and standard
orientation. Higher levels allowed when using the wall mounting bracket ZM2.WALL

Fig. 15-1 Output current vs. ambient temp.

Allowable Output Current at 24V

Allowed Output Current at 24V

24A

24A

C
A

20A

16A

12A

4A
0
-25

D
C
B
A

20A

B

16A

8A

Fig. 15-2 Output current vs. altitude

12A

0

20

40

A... Tamb < 60°C
B... Tamb < 50°C
C... Tamb < 40°C
D... Short term

8A

A...100 to 360Vdc, continuous
B... 88Vdc, continuous
C... Short term

4A
60 70°C

0
0

2000m

Ambient Temperature

4000m

6000m
Altitude

Apr. 2014 / Rev. 1.3 DS-CPS20.241-D1-EN
All parameters are specified at 24V, 20A, 300Vdc, 25°C ambient and after a 5 minutes run-in time unless otherwise noted.
www.pulspower.com Phone +49 89 9278 0Germany

14/25

CPS20.241-D1
24V, 20A, DC/DC CONVERTER

C-Series

16. PROTECTION FEATURES
Output protection
Output over-voltage protection

Electronically protected against overload, no-load and short-circuits*)
typ. 30.5Vdc
In case of an internal DC/DC converter defect, amax. 32Vdc
redundant circuit limits the maximum output voltage.
The output shuts down and automatically attempts torestart.
Degree of protection
IP 20
EN/IEC 60529
Caution: For use in a controlled environment according
to CSA 22.2 No 107.1-01.
Penetration protection> 5mme.g. screws, small parts
Over-temperature protection
yes
Output shut-down with automatic restart
Input transient protection
MOV (Metal Oxide Varistor)
Internal input fuse
DC suitable fuse included
not user replaceable
Reverse input polarity protection yes
unit does not start, no signalling*)

In case of a protection event, audible noise may occur.

17. SAFETY FEATURES
Input / output separation*)

Class of protection
Isolation resistancePE resistance
Touch current (leakage current)

*)

SELV
IEC/EN 60950-1
PELV
IEC/EN 60204-1, EN 50178, IEC 62103, IEC 60364-4-41
double or reinforced insulation
I
PE (Protective Earth) connection required> 5MOhm
input to output, 500Vdc< 0.1Ohm
The leakage current which is produced by the DC/DC converter itself depends on the
input voltage ripple and need to be investigated in the final application.
For a smooth DC input voltage, the produced leakage current is less than 100μA.

double or reinforced insulation

Apr. 2014 / Rev. 1.3 DS-CPS20.241-D1-EN
All parameters are specified at 24V, 20A, 300Vdc, 25°C ambient and after a 5 minutes run-in time unless otherwise noted.
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15/25

CPS20.241-D1
24V, 20A, DC/DC CONVERTER

C-Series

18. DIELECTRIC STRENGTH
The output voltage is floating and has no ohmic connection to the ground. Type and factory tests are conducted by
the manufacturer. Field tests may be conducted in the field using the appropriate test equipment which applies thevoltage with a slow ramp (2s up and 2s down). Connect all input-terminals together as well as all output poles before
conducting the test. When testing, set the cut-off current settings to the value in the table below.
Type test

60s

A
2500Vac

B
3000Vac

C
1000Vac

D
500VacFactory test

5s

2500Vac

2500Vac

500Vac

500VacField test

5s

2000Vac

2000Vac

500Vac

500Vac> 15mA> 15mA> 20mA> 1mA

Fig. 18-1 Dielectric strength

Input

DC-ok
B*)

+

-

Cut-off current setting
B

AD

To fulfil the PELV requirements according to EN60204-1 § 6.4.1, werecommend that either the + pole, the – pole or any other part ofthe output circuit shall be connected to the protective earthsystem. This helps to avoid situations in which a load starts
unexpectedly or can not be switched off when unnoticed earth
faults occur.

OutputEarth, PEC+-B*) When testing input to DC-OK ensure that the max. voltage between DC-OK and the output is not exceeded (column D). We recommend
connecting DC-OK pins and the output pins together when performing the test.

19. APPROVALSEC Declaration of Conformity

The CE mark indicates conformance with the- EMC directive 2004/108/EC,- Low-voltage directive (LVD) 2006/95/EC,- RoHS directive 2011/65/EU and the- ATEX directive 94/9/EC (for use in explosive atmospheres).
CB Scheme,
Information Technology Equipment

IEC 60950-1
2nd Edition
UL 508IND. CONT. EQ.

UL 60950-1
2nd Edition

ANSI / ISA 12.12.01-2007
Class I Div 2
EN 60079-0, EN 60079-15
ATEX
II 3G Ex nA nC II T3 Gc

IEC 60079-0, IEC 60079-15
GOST R

IECEx

Listed for use as Industrial Control Equipment;
U.S.A. (UL 508) and Canada (C22.2 No. 107-1-01);
E-File: E198865
Recognized for use as Information Technology Equipment,
Level 5; U.S.A. (UL 60950-1) and Canada (C22.2 No. 60950-1);
E-File: E137006
Applicable for altitudes up to 2000m.
Recognized for use in Hazardous Location Class I Div 2 T3Groups A,B,C,D systems; U.S.A. (ANSI / ISA 12.12.01-2007) andCanada (C22.2 No. 213-M1987)
Approval for use in hazardous locations Zone 2 Category 3G.
Number of ATEX certificate: EPS 13 ATEX 1 555 X
The DC/DC converter must be built-in in an IP54 enclosure.
Suitable for use in Class 1 Zone 2 Groups IIa, IIb and IIc
locations. Number of IECEx certificate: IECEx EPS 13.0016X
Certificate of Conformity for Russia and other GUS countries

Apr. 2014 / Rev. 1.3 DS-CPS20.241-D1-EN
All parameters are specified at 24V, 20A, 300Vdc, 25°C ambient and after a 5 minutes run-in time unless otherwise noted.
www.pulspower.com Phone +49 89 9278 0Germany

16/25

CPS20.241-D1
24V, 20A, DC/DC CONVERTER

C-Series

20. PHYSICAL DIMENSIONS AND WEIGHT
WeightDIN-Rail

Installation Clearances

940g / 2.1lb
Use 35mm DIN-rails according to EN 60715 or EN 50022 with a height of 7.5 or 15mm.
The DIN-rail height must be added to the unit depth (127mm) to calculate the total required
installation depth.
See chapter 2

Fig. 20-1 Front viewFig. 20-2 Side viewApr. 2014 / Rev. 1.3 DS-CPS20.241-D1-EN
All parameters are specified at 24V, 20A, 300Vdc, 25°C ambient and after a 5 minutes run-in time unless otherwise noted.
www.pulspower.com Phone +49 89 9278 0Germany

17/25

CPS20.241-D1
24V, 20A, DC/DC CONVERTER

C-Series

21. ACCESSORIES

21.1. ZM2.WALL - WALL MOUNTING BRACKETThis bracket is used to mount the DC/DC converter
onto a flat surface without utilizing a DIN-Rail.

21.2. ZM13.SIDE - SIDE MOUNTING BRACKETThis bracket is used to mount DIMENSION units sideways with or without utilizing a DIN-Rail. The two aluminum
brackets and the black plastic slider of the unit have to be detached, so that the steel brackets can be mounted.
For sideway DIN-rail mounting, the removed aluminum brackets and the black plastic slider need to be mounted on
the steel bracket.

Side mounting with DIN-rail brackets

Side mounting without DIN-rail brackets

Apr. 2014 / Rev. 1.3 DS-CPS20.241-D1-EN
All parameters are specified at 24V, 20A, 300Vdc, 25°C ambient and after a 5 minutes run-in time unless otherwise noted.
www.pulspower.com Phone +49 89 9278 0Germany

18/25

CPS20.241-D1
24V, 20A, DC/DC CONVERTER

C-Series

21.3. REDUNDANCY MODULES
YR40.242 – (2x 20A Inputs, 1x 40A output)
The YR40.242 is equipped with two input channels, which are individually decoupled byutilizing mosfet technology. Using mosfets instead of diodes reduces the heat generation andthe voltage drop between input and output. The YR40.242 does not require an additional
auxiliary voltage and is self-powered even in case of a short circuit across the output.
Due to the low power losses, the unit is very slender and only requires 36mm width on the
DIN-rail.

YR40.245 – (1x 40A input, 1x 40A output)
The YR40.245 is a 40A single channel redundancy module, which is equipped with a plugconnector on the output. The plug connector allows replacing the power supply or the
redundancy module while the system is running. The plug connector avoids that the output
wires can touch and short the load circuit.
The YR40.245 is very slender and only requires 46mm width on the DIN-rail. It also utilizes
mosfet technology instead of diodes for low heat generation and a minimal voltage drop
between input and output. It does not require an additional auxiliary voltage and is selfpowered even in case of a short circuit across the output.

Fig. 21-2 Typical N+1 or 1+1 Redundant configuration for 20A withmultiple YR40.245 redundancy modules

Fig. 21-1 Typical 1+1 Redundant configurationfor 20A with a dual redundancy module
24V
20A
Load

CPS20.241-D1
24-28V 480W
DC/DC
Converter+

YR40.242*)
Redundancy
ModuleDCOK

DC Input+ - PEFuse

Output24V 20A+ +- -CPS20.241-D1
24-28V 480W
DC/DC
Converter

CPS20.241-D1
24-28V 480W
DC/DC
Converter-

OutputInput Input
12+ - + -DC Input

Output24V 20A+ +DC Input- -+ - PE

OutputYR40.245
Redundancy
ModuleFuse

Output24V 20A+ +CPS20.241-D1
24-28V 480W
DC/DC
Converter

-

+

DCOK

DCOK

+ - PE

24V
20A
Load

FailureMonitorFailureMonitor- -Fuse

OutputYR40.245
Redundancy
Module

DCOK

Input

+

DC Input-+ - PE

Output24V 20A

+ +

-

+

- -

Input

+

-

Fuse

*) YR40.241

LNPE

also possible

L
N
PE

Apr. 2014 / Rev. 1.3 DS-CPS20.241-D1-EN
All parameters are specified at 24V, 20A, 300Vdc, 25°C ambient and after a 5 minutes run-in time unless otherwise noted.
www.pulspower.com Phone +49 89 9278 0Germany

19/25

CPS20.241-D1
24V, 20A, DC/DC CONVERTER

C-Series

22. APPLICATION NOTES
22.1. PEAK CURRENT CAPABILITY
The DC/DC converter can deliver peak currents (up to several milliseconds) which are higher than the specified shortterm currents. This helps to start current demanding loads. Solenoids, contactors and pneumatic modules often have asteady state coil and a pick-up coil. The inrush current demand of the pick-up coil is several times higher than thesteady-state current and usually exceeds the nominal output current (including the PowerBoost). The same situation
applies when starting a capacitive load.
The peak current capability also ensures the safe operation of subsequent circuit breakers of load circuits. The loadbranches are often individually protected with circuit breakers or fuses. In case of a short or an overload in one branch
circuit, the fuse or circuit breaker need a certain amount of over-current to open in a timely manner. This avoids
voltage loss in adjacent circuits.
The extra current (peak current) is supplied by the power converter and the built-in large sized output capacitors of
the DC/DC converter. The capacitors get discharged during such an event, which causes a voltage dip on the output.
The following two examples show typical voltage dips:
Fig. 22-2 Peak load with 5x the nominal
current for 5ms, typ.

Fig. 22-1 Peak load with 2x the nominal
current for 50ms, typ.
15ms

24V

OutputVoltage

24V

OutputVoltage
18V

100A

16V
40A

OutputCurrent

OutputCurrent

0A

0A

10ms/DIV

40A Peak load (resistive) for 50ms
Output voltage dips from 24V to 16V.

1ms/DIV

100A Peak load (resistive) for 5ms
Output voltage dips from 24V to 18V.

Fig. 22-3 90A Peak load, typ.

90A peakOutput Current

24V

Output Voltage
18V

15ms
0A

Please note: The DC-OK relay triggers when the voltage
dips more than 10% for longer than 1ms.

10ms/DIVHigh Overload Current (typ. 90A for15ms) enables easy fuse tripping
Peak current voltage dips

typ.
typ.
typ.

from 24V to 16Vfrom 24V to 18.5V
from 24V to 18V

at 40A for 50ms, resistive load
at 100A for 2ms, resistive load
at 100A for 5ms, resistive load

Apr. 2014 / Rev. 1.3 DS-CPS20.241-D1-EN
All parameters are specified at 24V, 20A, 300Vdc, 25°C ambient and after a 5 minutes run-in time unless otherwise noted.
www.pulspower.com Phone +49 89 9278 0Germany

20/25

CPS20.241-D1
24V, 20A, DC/DC CONVERTER

C-Series

22.2. INDUCTIVE AND CAPACITIVE LOADSThe unit is designed to supply any kind of loads, including capacitive and inductive loads. If extreme large capacitors,
such as EDLCs (electric double layer capacitors or “UltraCaps”) with a capacitance > 0.5F are connected to the output,
the unit might charge the capacitor in the HiccupPLUS-mode (see chapter 6).

22.3. EXTERNAL INPUT PROTECTION
The unit is tested and approved for branch circuits up to 30A (UL) and 32A (IEC). An external protection is only
required if the supplying branch has an ampacity greater than this. Provided, that the negative pole is grounded. If thepositive pole is grounded, an additional external fast-acting input fuse in the negative input is required (E.g. 8A KLKD
fuse from Littelfuse or a comparable UL-Listed fuse with the same ratings and characteristics). Otherwise the status of
the UL approvals becomes void.
Check also local codes and local requirements. In some countries local regulations might apply.
If an external fuse is necessary or utilized, minimum requirements need to be considered to avoid nuisance tripping of
the circuit breaker. A minimum value of 10A B- or C-Characteristic breaker should be used.

22.4. OUTPUT CIRCUIT BREAKERS
Standard miniature circuit breakers (MCB’s or UL1077 circuit breakers) are commonly used for AC-supply systems andmay also be used on 24V branches.
MCB’s are designed to protect wires and circuits. If the ampere value and the characteristics of the MCB are adapted to
the wire size that is used, the wiring is considered as thermally safe regardless of whether the MCB opens or not.
To avoid voltage dips and under-voltage situations in adjacent 24V branches which are supplied by the same source, afast (magnetic) tripping of the MCB is desired. A quick shutdown within 10ms is necessary corresponding roughly tothe ride-through time of PLC's. This requires DC/DC converters with high current reserves and large output capacitors.
Furthermore, the impedance of the faulty branch must be sufficiently small in order for the current to actually flow.
The best current reserve in the DC/DC converter does not help if Ohm’s law does not permit current flow. The
following table has typical test results showing which B- and C-Characteristic MCBs magnetically trip depending on thewire cross section and wire length.
Fig. 22-4 Test circuit

Power Supply

AC

MCB

+

+
Wire length

DC S1... Fault simulation switch

*)

Load

S1

-

Maximal wire length*) for a fast (magnetic) tripping:
0.75mm²
1.0mm²1.5mm²2.5mm²
C-2A
29m
40m
56m
82m
C-3A
26m
35m
50m
77m
C-4A
21m
28m
36m
53m
C-6A
8m
10m
14m
25m
C-8A
4m
7m
11m
18m
C-10A
1m
2m
3m
6m
B-6A
17m
24m
35m
53m
B-10A
12m
16m
23m
32m
B-13A
9m
13m
20m
29m
B-16A
4m
7m
9m
17m
B-20A
1m
1m
2m
2m

Don’t forget to consider twice the distance to the load (or cable length) when calculating the total wire length (+ and – wire).

Apr. 2014 / Rev. 1.3 DS-CPS20.241-D1-EN
All parameters are specified at 24V, 20A, 300Vdc, 25°C ambient and after a 5 minutes run-in time unless otherwise noted.
www.pulspower.com Phone +49 89 9278 0Germany

21/25

CPS20.241-D1
24V, 20A, DC/DC CONVERTER

C-Series

22.5. PARALLEL USE TO INCREASE OUTPUT POWER
CPS20.241-D1 DC/DC converter can be paralleled to increase the output
power. The output voltage of all DC/DC converters shall be adjusted to thesame value (±100mV) in “Single use” mode with the same load conditions on
all units, or the units can be left with the factory settings. After the
adjustments, the jumper on the front of the unit shall be moved from“Single use” to “Parallel use”, in order to achieve load sharing. The “Paralleluse” mode regulates the output voltage in such a manner that the voltage
at no load is approx. 4% higher than at nominal load. See also chapter 6. If
no jumper is plugged in, the unit is in “Single use” mode. Factory setting is“Single use” mode.

Unit A

Input+
Output+Unit B

Load

Input

+
-

-

OutputIf more than three units are connected in parallel, a fuse or circuit breaker with a rating of 30A or 32A is required oneach output. Alternatively, a diode or redundancy module can also be utilized.
Energize all units at the same time to avoid the overload HiccupPLUS mode. It also might be necessary to cycle the input
power (turn-off for at least five seconds), if the output was in HiccupPLUS mode due to overload or short circuits and therequired output current is higher than the current of one unit.
Keep an installation clearance of 15mm (left / right) between two DC/DC converters and avoid installing the DC/DC
converters on top of each other. Do not use DC/DC converters in parallel in mounting orientations other than thestandard mounting orientation (terminals on bottom of the unit) or in any other condition where a derating of theoutput current is required (e.g. altitude, above 60°C, …).
Pay attention that EMI and inrush current will increase when using multiple DC/DC converters.

22.6. PARALLEL USE FOR REDUNDANCY
DC/DC converters can be paralleled for redundancy to gain higher system availability. Redundant systems require acertain amount of extra power to support the load in case one DC/DC converter unit fails. The simplest way is to put
two DC/DC converters in parallel. This is called a 1+1 redundancy. In case one DC/DC converter unit fails, the other one
is automatically able to support the load current without any interruption. Redundant systems for a higher power
demand are usually built in a N+1 method. E.g. five DC/DC converter, each rated for 20A are paralleled to build a 80A
redundant system. For N+1 redundancy the same restrictions apply as for increasing the output power, see also section
22.5.
Please note: This simple way to build a redundant system does not cover failures such as an internal short circuit in
the secondary side of the DC/DC converter. In such a case, the defective unit becomes a load for the other DC/DC
converters and the output voltage can not be maintained any more. This can be avoided by utilizing redundancy
modules, which have decoupling devices (diodes or mosfets) included. Further information and wiring configurations
can be found in chapter 21.3.
Recommendations for building redundant power systems:
a)
b)
c)
d)

Use separate input fuses for each DC/DC converter.
Set the DC/DC converter into “Parallel use” mode.
Monitor the individual DC/DC converter units. Therefore, use the DC-OK relay contact of the CPS20 DC/DC
converter.
It is desirable to set the output voltages of all units to the same value (± 100mV) or leave it at the factory setting.

Apr. 2014 / Rev. 1.3 DS-CPS20.241-D1-EN
All parameters are specified at 24V, 20A, 300Vdc, 25°C ambient and after a 5 minutes run-in time unless otherwise noted.
www.pulspower.com Phone +49 89 9278 0Germany

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CPS20.241-D1
24V, 20A, DC/DC CONVERTER

C-Series

22.7. SERIES OPERATION
DC/DC converters of the same type can be connected in series for higher
output voltages. It is possible to connect as many units in series as needed,
providing the sum of the output voltage does not exceed 150Vdc. Voltages
with a potential above 60Vdc are not SELV any more and can be dangerous.
Such voltages must be installed with a protection against touching.

Unit A

Input+
OutputEarthing of the output is required when the sum of the output voltage isabove 60Vdc.

+

Unit B

Load

Input

+
-

Avoid return voltage (e.g. from a decelerating motor or battery) which isapplied to the output terminals.

OutputEarth(see notes)
Keep an installation clearance of 15mm (left / right) between two DC/DC
converters and avoid installing the DC/DC converters on top of each other. Do not use DC/DC converters in series inmounting orientations other than the standard mounting orientation (terminals on bottom of the unit).

Pay attention that EMI and inrush current will increase when using multiple DC/DC converters.

22.8. BACK-FEEDING LOADS
Loads such as decelerating motors and inductors can feed voltage back to the DC/DC converter. This feature is also
called return voltage immunity or resistance against Back- E.M.F. (Electro Magnetic Force).
This DC/DC converter is resistant and does not show malfunctioning when a load feeds back voltage to the DC/DC
converter. It does not matter whether the DC/DC converter is on or off.
The maximum allowed feed-back-voltage is 35Vdc. The absorbing energy can be calculated according to the built-in
large sized output capacitor which is specified in chapter 6.

Apr. 2014 / Rev. 1.3 DS-CPS20.241-D1-EN
All parameters are specified at 24V, 20A, 300Vdc, 25°C ambient and after a 5 minutes run-in time unless otherwise noted.
www.pulspower.com Phone +49 89 9278 0Germany

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CPS20.241-D1
24V, 20A, DC/DC CONVERTER

C-Series

22.9. CHARGING OF BATTERIESThe DC/DC converter can be used to charge lead-acid or maintenance free batteries. (Two 12V batteries in series)
Instructions for charging batteries:a)

Set output voltage (measured at no load and at the battery end of the cable) very precisely to the end-of-charge
voltage.
End-of-charge voltage

27.8V

27.5V

27.15V

26.8V

Battery temperature

10°C

20°C

30°C

40°C

b)

Use a 30A or 32A circuit breaker (or blocking diode) between the DC/DC converter and the battery.

c)Ensure that the output current of the DC/DC converter is below the allowed charging current of the battery.

d)Use only matched batteries when putting 12V types in series.

e)

The return current to the DC/DC converter (battery discharge current) is typ. 23mA when the DC/DC converter isswitched off (except in case a blocking diode is utilized).

22.10. USE IN A TIGHTLY SEALED ENCLOSURE
When the DC/DC converter is installed in a tightly sealed enclosure, the temperature inside the enclosure will behigher than outside. In such situations, the inside temperature defines the ambient temperature for the DC/DC
converter.
The following measurement results can be used as a reference to estimate the temperature rise inside the enclosure.
The DC/DC converter is placed in the middle of the box, no other heat producing items are inside the box
Enclosure:
Load:
Input:
Temperature inside enclosure:
Temperature outside enclosure:
Temperature rise:

Rittal Typ IP66 Box PK 9522 100, plastic, 254x180x165mm
24V, 16A; (=80%) load is placed outside the box
300Vdc
51.5°C (in the middle of the right side of the DC/DC converter with a distance of 2cm)
25.0°C
26.5K

Apr. 2014 / Rev. 1.3 DS-CPS20.241-D1-EN
All parameters are specified at 24V, 20A, 300Vdc, 25°C ambient and after a 5 minutes run-in time unless otherwise noted.
www.pulspower.com Phone +49 89 9278 0Germany

24/25

CPS20.241-D1
24V, 20A, DC/DC CONVERTER

C-Series22.11. MOUNTING ORIENTATIONSMounting orientations other than all terminals on the bottom require a reduction in continuous output power or alimitation in the maximum allowed ambient temperature. The amount of reduction influences the lifetime expectancyof the DC/DC converter. Therefore, two different derating curves for continuous operation can be found below:
Curve A1
Curve A2

Recommended output current.
Max allowed output current (results in approximately half the lifetime expectancy of A1).

Fig. 22-5
Mounting
Orientation A(Standardorientation)

Output Current

24A

A1

18
DC/DC
Converter

12
6
Ambient Temperature0

INPUT OUTPUT

10
Fig. 22-6
Mounting
Orientation B(Upside down)

20

30

50

40

60°C

Output Current

24A
A1

INPUT OUTPUT

18

A2

DC/DC
Converter

12
6
Ambient Temperature

010Fig. 22-7
Mounting
Orientation C(Table-top
mounting)

20

30

50

40

60°C

Output Current

24A
A1

18

A2

12
6
Ambient Temperature

0
10

50

40

60°C

24A
DC/DC
Converter

18

A1

12

A2

6
Ambient Temperature

0
10

20

30

40

A1

A2

50

60°C

Output Current
INPUT OUTPUT

24A
DC/DC
Converter

Fig. 22-9
Mounting
Orientation E(Horizontal ccw)

30

Output Current
INPUT OUTPUT

Fig. 22-8
Mounting
Orientation D(Horizontal cw)

20

18
12
6

Ambient Temperature

0
10

20

30

40

50

60°C

Apr. 2014 / Rev. 1.3 DS-CPS20.241-D1-EN
All parameters are specified at 24V, 20A, 300Vdc, 25°C ambient and after a 5 minutes run-in time unless otherwise noted.
www.pulspower.com Phone +49 89 9278 0Germany

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