CPS20.241-60
24V, 400W, DC/DC CONVERTER

C-Series

DC/DC CONVERTER
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
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EN 50155 Railway Compliant
Conformal Coated PC-boards
Built-in Redundancy (Decoupling Mosfet at the Output)
Quick-connect Spring-clamp Terminals
77-154Vdc Wide-range Input
Width only 65mm
Efficiency up to 93.7%
Excellent Partial Load Efficiency
Safe HiccupPLUS Overload Mode
Minimal Inrush Current Surge
Full Power Between -40°C and +70°C
DC-OK Relay Contact
Reverse Input Polarity Protected
3 Year Warranty

GENERAL DESCRIPTIONSHORT-FORM DATAThe CPS20.241-60 DC/DC converter is designed
specifically for railway & transportation applications. It
is approved according to the EN 50155 standard, which
is an international standard covering electronicequipment used on rolling stock for railway
applications. The standard covers aspects such astemperature, humidity, shock, vibration, EMI and otherparameters. Because of these requirements, the unit isequipped with conformal coated pc-boards.

Output voltage
Adjustment range
Output current
Output power
Output ripple
AC Input voltage
DC Input voltage
DC Input current
Inrush current
Efficiency
LossesTemperature range
Derating
Hold-up time
Dimensions
WeightThe unit features a DC-OK signal contact for remotemonitoring, a decoupling MOSFET for building
redundant power supply systems and quick-connect
spring-clamp terminals for a reliable connection evenwhen mechanical vibration and shock are involved. The
unit also covers an extreme wide temperature range
from -40°C up to +70°C with full output current.
This DC/DC converter comes in a very compact housing
and requires only 65mm space on the DIN-rail due tothe high efficiency and low power losses. The highefficiency is achieved by utilizing cutting edge
technology and other unique design techniques.

ORDER NUMBERS

DC 24.5V
not adjustable
16.3A
400W
max. 100mVpp 20Hz to 20MHz
DC 110V- 30%/ +40%
3.87A
at 110Vdc
typ. 6A peakat 110Vdc
93.7%
at 110Vdc
26.9W
at 110Vdc-40°C to +70°C operational
not required
typ. 35ms
at 110Vdc
65x124x127mm WxHxD
980g / 2.16lb

MARKINGS

DC/DC converter CPS20.241-60
Accessory

ZM2.WALL
ZM13.SIDE

Wall mount bracket
Side mount bracket

EMC, LVD

Sep. 2019 / Rev. 1.1 DS-CPS20.241-60-EN
All parameters are specified at 24.5V, 16.3A, 110Vdc, 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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CPS20.241-60
24V, 400W, 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 .......................................................7
8. DC-OK Relay Contact ..........................................7
9. Efficiency and Power Losses................................8
10. Lifetime Expectancy and MTBF...........................8
11. Functional Diagram.............................................912. Terminals and Wiring ..........................................9
13. Front Side and User Elements ...........................10
14. EMC ....................................................................11
15. Environment ......................................................12
16. Protection Features ...........................................13
17. Safety Features ..................................................13
18. Dielectric Strength ............................................14
19. Approvals and Declarations ..............................15Page
20. RoHS, REACH and Other Fulfilled Standards .. 15
21. Physical Dimensions and Weight ..................... 16
22. Accessories ........................................................ 1722.1. ZM2.WALL - Wall Mounting Bracket ....... 1722.2. ZM13.SIDE - Side Mounting Bracket ........ 17
23. Application Notes ............................................. 18
23.1. Peak Current Capability ........................... 18
23.2. Inductive and Capacitive Loads................ 18
23.3. External Input Protection ......................... 19
23.4. Output Circuit Breakers............................ 19
23.5. Charging of Batteries ............................... 19
23.6. Parallel Use to Increase Output Power .... 20
23.7. Parallel Use for Redundancy .................... 20
23.8. Series Operation ....................................... 21
23.9. Back-feeding Loads .................................. 2123.10. Use in a Tightly Sealed Enclosure ............ 21
23.11. Mounting Orientations ............................ 22

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 110V

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)

110VdcA 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.

Sep. 2019 / Rev. 1.1 DS-CPS20.241-60-EN
All parameters are specified at 24.5V, 16.3A, 110Vdc, 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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CPS20.241-60
24V, 400W, 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 inrolling stock for railway applications or in industrial 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.

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 23.11.
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).

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.

Sep. 2019 / Rev. 1.1 DS-CPS20.241-60-EN
All parameters are specified at 24.5V, 16.3A, 110Vdc, 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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CPS20.241-60
24V, 400W, DC/DC CONVERTER

C-Series

3. AC-INPUT
Do not operate this DC/DC converter with an AC-input voltage. Use the CPS20.241 or CPS20.241-C1 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.
Input voltage
Input voltage range

nom.

Input current
Allowed voltage between input
to earth (ground)
Allowed input ripple voltage

typ.
max.

Shut-down voltage
Start-up delay
Rise timeTurn-on overshootExternal input protection

max.

Rated
input range

50Hz –10kHz
10kHz – 50kHz
typ.
steady-state value, at ambient temperatures between-20°C and +70°C, see Fig. 4-1
typ.
85Vdc
steady-state value, at -40°C ambient temperature
typ.
60Vdc
steady-state value, see Fig. 4-1
typ.
900ms
see Fig. 4-2
typ.
85ms
at 16.3A constant current load, 0mF load capacitance,
see Fig. 4-2
typ.
130ms
at 16.3A constant current load, 20mF load capacitance,
see Fig. 4-2
max.
200mV
see Fig. 4-2
See recommendations in chapter 23.3.
Fig. 4-2 Turn-on behavior, definitions

max.
500ms

Turn-onShut-down

short term for 100ms
at 16.3A and 110Vdc input voltage, see Fig. 4-3
continuous, IEC 62103

15Vpp
3Vpp
77Vdc

Fig. 4-1 Input voltage range

POUT-30%/+40%

Input
Voltage

OutputVoltage

VIN
77V

154V

- 5%
Start-up
delay

Rise
Time

OvershootTurn-on voltage

DC 110V
77-154Vdc
66-77Vdc
3.87A
375Vdc375VdcSep. 2019 / Rev. 1.1 DS-CPS20.241-60-EN
All parameters are specified at 24.5V, 16.3A, 110Vdc, 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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CPS20.241-60
24V, 400W, DC/DC CONVERTER

C-Series

Fig. 4-3 Input current vs. output load
Input Current at 110Vdc input, typ.

5A
4
3
2
1
0

0

2

4

6

8

10

12

14 16 18A

Output Current

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

max.
typ.
max.

13Apeak
6Apeak
1A2s

at 110Vdc, temperature independent
at 110Vdc, temperature independent
at 110Vdc, temperature independentFig. 5-1 Typical input inrush current behaviour at nominal load and
25°C ambient

Sep. 2019 / Rev. 1.1 DS-CPS20.241-60-EN
All parameters are specified at 24.5V, 16.3A, 110Vdc, 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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CPS20.241-60
24V, 400W, DC/DC CONVERTER

C-Series

6. OUTPUT
Output voltage

nom.

Adjustment range
Line regulation
Load regulation
Ripple and noise voltage
Output current
Output power
Overload behaviour

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

Short-circuit current

min.
max.
max.

24.5V ***)
25.0V ***)
10mV
500mV ***)
100mVpp
16.3A
400W
cont. current
HiccupPLUS mode*)
25A**)
32A**)
11A**)

Output capacitancetyp.

7 000µF

*)

**)
***)

±2%, at 16.3A load current±2%, at 0A load current
fixed output voltage, no adjustments possible
77-154Vdc
static value, 0A  16.3A
20Hz to 20MHz, 50Ohm
continuously available
continuously available
output voltage > 13Vdc, see Fig. 6-1
output voltage < 13Vdc, see Fig. 6-1
load impedance <10mOhm, see Fig. 6-2.
load impedance <10mOhm, see Fig. 6-2.
average (R.M.S.) current, load impedance 50mOhm,
see Fig. 6-2.
included inside the DC/DC converter

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. 6-2.
Discharge current of output capacitors is not included.
The unit is featured with a “soft output regulation characteristic” in order to achieve current share between multiple DC/DC
converters, when they are connected in parallel (.g. for redundancy reasons).
Fig. 6-1 Output voltage vs. output current,
typ.

Output Voltage

28V

Continuous current

24

Fig. 6-2 Short-circuit on output, HiccupPLUS mode,
typ.
OutputCurrent

20

Normaloperation

Normaloperation

Short -circuit

29A

16
12
HiccupPLUS
mode

8
4
0

t

0

0

3

6

9 12 15 18 21 24 27 30A

2s

18s

2s

18s

2s

18s

Output Current

Sep. 2019 / Rev. 1.1 DS-CPS20.241-60-EN
All parameters are specified at 24.5V, 16.3A, 110Vdc, 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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CPS20.241-60
24V, 400W, 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 Time

typ.
min.
typ.
min.

80ms
64ms
35ms
28ms

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

at 8.2A, see Fig. 7-1
at 8.2A, see Fig. 7-1
at 16.3A, see Fig. 7-1
at 16.3A, see Fig. 7-1
Fig. 7-2 Shut-down behavior, definitions

Hold-up Time

Input
Voltage

100ms
at 8.2A, typ.

80

at 8.2A, min.

60
40

at 16.3A, typ.

20

at 16.3A, min.

0

70

90

110

130

- 5%

OutputVoltage
Hold-up Time

150VdcInput Voltage

8. 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
Contact ratings
Isolation voltage

As soon as the output voltage reaches 22V.
As soon as the output voltage falls below 22V.
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.

Fig. 8-1 DC-ok relay contact behavior

22V
<
1ms

open

closed

>
1ms

100ms

open

closedSep. 2019 / Rev. 1.1 DS-CPS20.241-60-EN
All parameters are specified at 24.5V, 16.3A, 110Vdc, 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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CPS20.241-60
24V, 400W, DC/DC CONVERTER

C-Series

9. EFFICIENCY AND POWER LOSSES
Efficiency
Average efficiency*)

typ.
typ.

93.7%
92.3%

Power losses

typ.
typ.
typ.

4.7W
17.4W
26.9W

*)

at 110Vdc input and 16.3A output current
25% at 4.1A, 25% at 8.2A,
25% at 12.2A. 25% at 16.3A
at 110Vdc input and 0A output current
at 110Vdc input and 8.2A output current
at 110Vdc input and 16.3A output current

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, typFig. 9-2 Losses vs. output current, typ.

Efficiency

Power Losses

94%
93
92
91
90
89
88
87

30W
25
20
15
10
5
2

4

6

8

10

12

14

16A

Output Current

0

Output Current

0

2

4

6

8

10

12

14 16A

10. LIFETIME EXPECTANCY AND MTBF
Lifetime expectancy*)

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

222 000h*)
627 000h*)
151 000h*)
428 000h*)
571 000h
932 000h
238 000h
322 000h
51 000h
67 000hat 8.2A and 40°C
at 8.2A and 25°C
at 16.3A and 40°C
at 16.3A and 25°C
at 16.3A and 40°C
at 16.3A and 25°C
at 16.3A and 40°C, Ground Benign GB40
at 16.3A and 25°C, Ground Benign GB25
at 16.3A and 40°C, Ground Fixed GF40
at 16.3A 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.
*)

Sep. 2019 / Rev. 1.1 DS-CPS20.241-60-EN
All parameters are specified at 24.5V, 16.3A, 110Vdc, 25°C ambient and after a 5 minutes run-in time unless otherwise noted.
www.pulspower.com Phone +49 89 9278 0Germany

8/22

CPS20.241-60
24V, 400W, DC/DC CONVERTER

C-Series

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

Input Fuse
Input Filter
Active Inrush
Limiter

Reverse Polarity
andBack-feeding
Protection

Boost
Converter(preconditioning)

Power
Converter

OutputFilterDecoupling*)++-

OutputVoltage
Regulator
Temperature
Shutdown*)

OutputPower
Manager

OutputOverVoltage
Protection

OutputVoltage
Monitor

DC-ok
LED
DC-ok
Relay

DC-ok
Contact

Decoupling: This feature utilizes a Mosfet instead of a diode in order to minimize the voltage drop and power losses.

12. TERMINALS AND WIRING
The terminals are IP20 finger safe constructed and suitable for field- and factory wiring. Shipped in open position.
Type
Solid wire
Stranded wire
American Wire Gauge
Max. wire diameter
Wire stripping length
Screwdriver
Recommended tightening torque

Input and output
Bi-stable, quick-connect spring-clamp
terminals
max. 6mm2
max. 4mm2
AWG20-10
2.8mm (including ferrules)
10mm / 0.4inch
not required
not applicable

DC-OK-Signal
push-in spring-clamp terminals
max. 1.5mm2
max. 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) Ferrules are allowed.

Sep. 2019 / Rev. 1.1 DS-CPS20.241-60-EN
All parameters are specified at 24.5V, 16.3A, 110Vdc, 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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CPS20.241-60
24V, 400W, DC/DC CONVERTER

C-Series

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

DC/DC
Converter+ + Output-

Fig. 12-2 Using distribution terminals

DC/DC
Converter+ + --OutputDC/DC
Converter

Load

+ + -

-

+

-

DC/DC
Converter+ + --OutputOutputDistribution
Terminals
Load
+

-

max 25A!
continuous

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

Input Terminals (quick-connect spring-clamp terminals)+
Positive input–
Negative (return) input
PE (Protective Earth) input

B

Output Terminals (quick-connect spring-clamp terminals)+
Positive output–
Negative (return) output

C

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

D DC-OK LED (green)
On, when the output voltage is >22V.

Sep. 2019 / Rev. 1.1 DS-CPS20.241-60-EN
All parameters are specified at 24.5V, 16.3A, 110Vdc, 25°C ambient and after a 5 minutes run-in time unless otherwise noted.
www.pulspower.com Phone +49 89 9278 0Germany

10/22

CPS20.241-60
24V, 400W, DC/DC CONVERTER

C-Series

14. EMCThe DC/DC converter is suitable for rolling stock railway applications, for applications in industrial environment as wellas in residential commercial and light industry environment without any restrictions.
EMC Immunity

According generic standards: EN 61000-6-1 and EN 61000-6-2 andaccording to EN 50121-3-2
Electrostatic discharge
EN 61000-4-2
contact discharge
8kV
air discharge
15kVElectromagnetic RF field
EN 61000-4-3
80MHz-2.7GHz
20V/m
Fast transients (Burst)
EN 61000-4-4
input lines
4kV
output lines
2kV
DC-OK signal (coupling clamp)
2kV
Surge voltage on input
EN 61000-4-5+2kV+  PE, -  PE
4kV
Surge voltage on output
EN 61000-4-5+1kV+ / -  PE
2kV
Surge voltage on DC-OK
EN 61000-4-5
DC-OK signal  PE
1kV
Conducted disturbanceEN 61000-4-6
0.15-80MHz
10V
Power – Frequency magnetic EN 61000-4-8
16.7Hz, 50Hz
100A/mfield
Power – Frequency magnetic EN 61000-4-8
0Hz
300A/mfield
Pulsed magnetic field
EN 61000-4-9
300A/mCriterion A
Criterion A
Criterion A
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.

EMC Emission

According generic standards: EN 61000-6-3 and EN 61000-6-4
and according to EN 50121-3-2
Conducted emission
CISPR 16-1-2, CISPR 16-2-1
limits for EN 50121-3-2 fulfilled,
input lines
limits for DC power port
according EN 61000-6-3 fulfilled
Conducted emission
CISPR 16-1-2, CISPR 16-2-1
limits for EN 50121-3-2 fulfilled,
output lines
limits for DC power port
according EN 61000-6-3 not
fulfilled *)Radiated emission
EN 55011, EN 55022, EN 50121-3-2Class 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

Sep. 2019 / Rev. 1.1 DS-CPS20.241-60-EN
All parameters are specified at 24.5V, 16.3A, 110Vdc, 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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CPS20.241-60
24V, 400W, DC/DC CONVERTER

C-Series

15. ENVIRONMENT
Conformal coating
Operational temperature*)

yes-40°C to +70°C (-40°F to 158°F)

Storage temperature
Output de-rating+70°C to +85°C (158°F to 185°F)-40 to +85°C (-40°F to 185°F)
0.08A/V at +70°C or
0.16A/°C at 77Vdc

Humidity **)Vibration sinusoidal

all pc-boards are conformal coatedcontinuous operation, reduce output power
according Fig. 15-1 for input voltages below
100Vdcfor maximal 10 minutes every hourfor storage and transportation
required for input voltage smaller than 100Vdc
in combination with ambient temperatures
above +60°C (140°F).
Derate linearly between 100Vdc and 77Vdc or+60°C and +70°C, see Fig. 15-1.
IEC 60068-2-30
IEC 60068-2-6; DC/DC converter in operation

Vibration broadband

5 to 95% r.h.
2-17.8Hz: ±1.6mm; 17.8-500Hz: 2g***)2 hours / axis
1.01grms for 10 minutes; 5-150Hz***)Vibration broadband

5.72grms for 300 minutes; 5-150Hz***)Shock

30g 6ms, 20g 11ms, 50g 30ms***)3 bumps / direction, 18 bumps in total
50g 30ms***)3 bumps / direction, 18 bumps in total
0 to 2000m (0 to 6 560ft)
2000 to 6000m (6 560 to 20 000ft)

Shock

IEC 60068-2-64, DC/DC converter in operation;
Tests limits according to EN 61373
IEC 60068-2-64, DC/DC converter not in
operation; Tests limits according to EN 61373
IEC 60068-2-27; DC/DC converter in operation

IEC 60068-2-27, DC/DC converter not in
operation; Tests limits according to EN 61373
without any restrictions
reduce output power or ambient temperature,
see Fig. 15-2
IEC 62103, EN 50178, overvoltage category II
24W/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

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.

Allowed Output Current

18A

18A

A

16.3A

15

B

12

C

9
6
3
0
-40

Fig. 15-2 Output current vs. altitude

Allowable Output Current
16.3A

15
12
9

A...100 to 154Vdc, continuous
B... 77 to 100Vdc, continuous
C... for maximal 10 minutes

-20

0

20

40

60 70 85°C

Ambient Temperature

C
B
A

A... Tamb < 70°C
B... Tamb < 60°C
C... Tamb < 50°C

6
3
0

0

2000m

4000m

6000m
AltitudeSep. 2019 / Rev. 1.1 DS-CPS20.241-60-EN
All parameters are specified at 24.5V, 16.3A, 110Vdc, 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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CPS20.241-60
24V, 400W, 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, aredundant circuit limits the maximum output voltage.
max. 32Vdc
The output shuts down and automatically attempts torestart.
Degree of protection
IP 20
EN/IEC 60529
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 isolation to the input voltageI
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.

Sep. 2019 / Rev. 1.1 DS-CPS20.241-60-EN
All parameters are specified at 24.5V, 16.3A, 110Vdc, 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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CPS20.241-60
24V, 400W, 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

DC-ok

Input
B

+

*)

-

Cut-off current setting
B

A

D
OutputEarth, PEC+-

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.

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.

Sep. 2019 / Rev. 1.1 DS-CPS20.241-60-EN
All parameters are specified at 24.5V, 16.3A, 110Vdc, 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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CPS20.241-60
24V, 400W, DC/DC CONVERTER

C-Series

19. APPROVALS AND DECLARATIONSEC Declaration of Conformity

Railway applications - Electronicequipment used on rolling stock.
EN 50155:2007

The CE mark indicates conformance with the- EMC directive and the- Low-voltage directive
The manufacturer’s declaration indicate conformance withthe following characteristics:- Altitude category: AX (EN 50125-1 § 4.2.1)- Environmental category: TX (EN 50155 § 4.1.2)- Interruption of voltage supply: S2 (EN 50155 § 5.1.1.2)- Supply change over: C2 (EN 50155 § 5.1.3)- Shock and vibration: Category 1, Class A and B (EN 61373)- EMI: EN 50121-3-2- Fire Classification: HL3 (EN 45545-2)

20. ROHS, REACH AND OTHER FULFILLED STANDARDSRoHS Directive

REACH Directive

Directive 2011/65/EU of the European Parliament and theCouncil of June 8th, 2011 on the restriction of the use ofcertain hazardous substances in electrical and electronicequipment.
Directive 1907/2006/EU of the European Parliament and theCouncil of June 1st, 2007 regarding the Registration,
Evaluation, Authorisation and Restriction of Chemicals(REACH)

Sep. 2019 / Rev. 1.1 DS-CPS20.241-60-EN
All parameters are specified at 24.5V, 16.3A, 110Vdc, 25°C ambient and after a 5 minutes run-in time unless otherwise noted.
www.pulspower.com Phone +49 89 9278 0Germany

15/22

CPS20.241-60
24V, 400W, DC/DC CONVERTER

C-Series

21. PHYSICAL DIMENSIONS AND WEIGHT
Width
HeightDepth

WeightDIN-Rail
Housing material
Installation clearances

65mm 2.56’’124mm 4.88’’127mm 5.0’’
The DIN-rail height must be added to the unit depth to calculate the total required
installation depth.
980g / 2.16lb
Use 35mm DIN-rails according to EN 60715 or EN 50022 with a height of 7.5 or 15mm.
Body: Aluminium alloy
Cover: zinc-plated steel
See chapter 2

Fig. 21-1 Front viewFig. 21-2 Side viewSep. 2019 / Rev. 1.1 DS-CPS20.241-60-EN
All parameters are specified at 24.5V, 16.3A, 110Vdc, 25°C ambient and after a 5 minutes run-in time unless otherwise noted.
www.pulspower.com Phone +49 89 9278 0Germany

16/22

CPS20.241-60
24V, 400W, DC/DC CONVERTER

C-Series

22. ACCESSORIES

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

Due to the small size of the unit, it is required that the black-DIN-rail slide on the back of the unit must be removed.
Instructions how to do this can be found in the manual of the ZM2.WALL.

22.2. 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

Sep. 2019 / Rev. 1.1 DS-CPS20.241-60-EN
All parameters are specified at 24.5V, 16.3A, 110Vdc, 25°C ambient and after a 5 minutes run-in time unless otherwise noted.
www.pulspower.com Phone +49 89 9278 0Germany

17/22

CPS20.241-60
24V, 400W, DC/DC CONVERTER

C-Series

23. APPLICATION NOTES
23.1. 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. The same situation applies when starting acapacitive 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 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. 23-1 Peak load with 2x the nominal
current for 50ms, typ.

Fig. 23-2 Peak load with 5x the nominal
current for 5ms, typ.

32.6A Peak load (resistive) for 50ms
Output voltage dips from 24.5V to 17V.

81.5A Peak load (resistive) for 5ms
Output voltage dips from 24.5V to 9V.

Peak current voltage dips

typ.
typ.
typ.

from 24.5V to 17Vfrom 24.5V to 18Vfrom 24.5V to 9V

at 32.6A for 50ms, resistive load
at 81.5A for 2ms, resistive load
at 81.5A for 5ms, resistive load

23.2. 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).

Sep. 2019 / Rev. 1.1 DS-CPS20.241-60-EN
All parameters are specified at 24.5V, 16.3A, 110Vdc, 25°C ambient and after a 5 minutes run-in time unless otherwise noted.
www.pulspower.com Phone +49 89 9278 0Germany

18/22

CPS20.241-60
24V, 400W, DC/DC CONVERTER

C-Series23.3. 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.
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.

23.4. 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. 23-3 Test circuit

Power Supply

AC

MCB

Load

+

+
Wire length

DC -

S1

-

S1... Fault simulation switch*)

Maximal wire length*) for a fast (magnetic) tripping:
0.75mm²
1.0mm²1.5mm²2.5mm²
C-2A
30m
40m
49m
85m
C-3A
19m
24m
35m
52m
C-4A
11m
15m
22m
31m
C-6A
4m
6m
8m
11m
C-8A
1m
1m
2m
3m
C-10A
1m
1m
2m
3m
B-6A
10m
14m
22m
34m
B-10A
3m
5m
10m
13m
B-13A
2m
4m
7m
10m

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

23.5. CHARGING OF BATTERIESThe DC/DC converter can not be used to charge batteries.

Sep. 2019 / Rev. 1.1 DS-CPS20.241-60-EN
All parameters are specified at 24.5V, 16.3A, 110Vdc, 25°C ambient and after a 5 minutes run-in time unless otherwise noted.
www.pulspower.com Phone +49 89 9278 0Germany

19/22

CPS20.241-60
24V, 400W, DC/DC CONVERTER

C-Series23.6. PARALLEL USE TO INCREASE OUTPUT POWER
CPS20.241-60 DC/DC converters can be paralleled to increase the output power as long as the ambient temperature
stays below 60°C.
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.
Fig. 23-4 Parallel use to increase the output power- 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.

Unit A

Input+-

Output- Do not parallel DC/DC converters in orientations otherthan the standard mounting orientation (terminals onbottom of the unit) or in any other condition where aderating of the output current is required (e.g. altitude,
temperature, input voltages).

+

Unit B

Load

Input

-

+
-

OutputInstructions for parallel use:

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

23.7. PARALLEL USE FOR REDUNDANCYCPS20.241-60 DC/DC converters can be paralleled for redundancy to gain higher system availability. Redundant systems
require a certain 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, theother 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 16A are paralleled to build
a 64A redundant system. For N+1 redundancy the same restrictions apply as for increasing the output power, see also
section 23.6.
Since the CPS20.241-60 already has decoupling MOSFETS included, which cover failures such as an internal short circuitin the secondary side of the DC/DC converter, no additional redundancy modules are required.
Fig. 23-5 Redundant power design
FailureMonitor
CPS20.241-60
24.5V 400W
Power
SupplyCPS20.241-60
24.5V 400W
Power
Supply

DCOK

Input

+

- PE

DCOK

Output

+ +

- -

Input

+

- PE

Recommendations for building redundant powersystems:- Use separate input fuses for each DC/DC
converter.
- Monitor the individual DC/DC converter units.
Use the DC-OK relay contact of the CPS20.241-60.

Output

+ +

- 24V
20A
Load

I

I

+

-

PE

Sep. 2019 / Rev. 1.1 DS-CPS20.241-60-EN
All parameters are specified at 24.5V, 16.3A, 110Vdc, 25°C ambient and after a 5 minutes run-in time unless otherwise noted.
www.pulspower.com Phone +49 89 9278 0Germany

20/22

CPS20.241-60
24V, 400W, DC/DC CONVERTER

C-Series

23.8. 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 apotential above 60Vdc are not SELV any more and can be dangerous. Such voltages must be installed with a protection
against touching.
Avoid return voltage (e.g. from a decelerating motor or battery) which is applied to the output terminals.
Fig. 23-6 Wiring scheme for series operation
Unit A

Input

Output- 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.

++

Unit B

Input

OutputInstructions for series use:

Load

-

+
-

- Do not use DC/DC converters in series in mounting
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.

23.9. 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.

23.10. 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, 13A; (=80%) load is placed outside the box
110Vdc
44.5°C (in the middle of the right side of the DC/DC converter with a distance of 2cm)
23.2°C
21.3K

Sep. 2019 / Rev. 1.1 DS-CPS20.241-60-EN
All parameters are specified at 24.5V, 16.3A, 110Vdc, 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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CPS20.241-60
24V, 400W, DC/DC CONVERTER

C-Series23.11. 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. 23-7
Mounting
Orientation A(Standardorientation)

Output Current

20A

16.3A

15A
DC/DC
Converter

A1

10A
5A
Ambient Temperature0

INPUT OUTPUT

20
Fig. 23-8
Mounting
Orientation B(Upside down)

30

40

50

60

Output Current

20A

16.3A

INPUT OUTPUT

15A

A2
A1

DC/DC
Converter

10A
5A
Ambient Temperature

020
Fig. 23-9
Mounting
Orientation C(Table-top
mounting)

30

40

50

60

20A

16.3A

15A
10A

A2
A1

Ambient Temperature

0
20

30

40

50

60

70°C

Output Current

20A

DC/DC
Converter

INPUT OUTPUT

16.3A

15A
10A

A2
A1

5A

Ambient Temperature

0
20

30

40

50

60

70°C

Output Current
INPUT OUTPUT

20A

DC/DC
Converter

Fig. 23-11
Mounting
Orientation E(Horizontal ccw)

70°C

Output Current

4A

Fig. 23-10
Mounting
Orientation D(Horizontal cw)

70°C

16.3A

15A
10A

A2
A1

5A

Ambient Temperature

0
20

30

40

50

60

70°C

Sep. 2019 / Rev. 1.1 DS-CPS20.241-60-EN
All parameters are specified at 24.5V, 16.3A, 110Vdc, 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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