3500/70M Recip Impulse Velocity Monitor
Datasheet

Bently Nevada Machinery Condition Monitoring

166766 Rev. PDescription
The 3500/70M Recip Impulse Velocity Monitor is a 4-channel
device used as part of the reciprocating compressor
solutions package to monitor compressor crankcase andcrosshead vibration. The monitor accepts input from seismictransducers, conditions the signal to derive vibration
measurements, and compares the conditioned signals withuser-programmable alarms.
You can program each channel using the 3500 Rack
Configuration Software to perform the following functions:llll

Impulse Acceleration
Acceleration 2
Recip Velocity
Low Frequency Recip Velocity
The monitor channels are programmed in pairs and canperform up to two of the aforementioned functions at atime. For example, channels 1 and 2 can perform one
function while channels 3 and 4 perform another or thesame function.

The primary purpose of the 3500/70M Recip Impulse Velocity
Monitor is to provide the following:llMachinery protection for reciprocating compressors bycontinuously comparing monitored parametersagainst configured alarm setpoints to drive alarms
Essential reciprocating compressor machine
information for both operations and maintenancepersonnel

Each channel, depending on configuration, typicallyconditions its input signal to generate various parameters
called static values. You can configure alert setpoints foreach active static value and danger setpoints for any two of
the active static values.

3500/70M Recip Impulse Velocity Monitor
Datasheet

166766 Rev. P

Specifications
InputsSignal

Accepts from 1 to 4 proximity
probe signals.

Input
impedance

10 kΩ acceleration input>1 MΩ velocity input

Special inhibit

Contact closure
5 Vdc @ 390μA typicalPowerconsumption

7.7 watts, nominal

Current

40 mA maximum
15 mA maximum on startup
to guarantee no fold back

Outputimpedance

20 Ω typical operating1000 Ω typical under foldback conditions

Protection

Foldback current
15.4 to 24.9 mA

Front Panel Buffered Outputs

Sensitivity

BufferedTransducer
Outputs

The front of each monitor
has one coaxial connector
for each channel.

OutputImpedance

550 Ω typical
Each connector is shortcircuit protected.

Impulseacceleration

0.51 – 11.72 mV/(m/s2)
5 – 115 mV/g

Protection

Acceleration 20.51 – 11.72 mV/(m/s2)
5 – 115 mV/g

Recorder Outputs

Recip velocity

3.54 – 22.64 mV/(mm/s)
90 – 575 mV/(in/s)

Low Frequency
Recip velocity

3.54 – 22.64 mV/(mm/s)
90 – 575 mV/(in/s)

Outputs
Front Panel LEDs

OK LED

Indicates when the
3500/70M Recip Impulse
Velocity Monitor is operating
properly.

TX/RX LED

Indicates when the
3500/70M Recip Impulse
Velocity Monitor iscommunicating with othermodules in the 3500 rack.

Bypass LED

Indicates when the
3500/70M Recip Impulse
Velocity Monitor is in Bypass
Mode.

Transducer Power Supply
Voltage-22 Vdc minimum

2/15

Recorder+4 to +20 mA proportional tomonitor full-scale.
Selects one static data value
from each channel to be
used for that channel’srecorder value.

Voltagecompliance+12 Vdc maximum

Loadresistance600 Ω maximum

Resolution

0.3662 µA maximum

Update rate

<100 millisecond

Accuracy

Within ±0.05 mA.
±0.14 mA over temperature
range.

3500/70M Recip Impulse Velocity Monitor
Datasheet

166766 Rev. P

Signal Conditioning

Acceleration 2

Specified at +25ºC (+77ºF) unlessotherwise noted.

Within ± 0.33% of full-scale
typical± 1% maximum
Exclusive of filters

Accuracy

Impulse Acceleration

Frequency Response
Accuracy

Within ± 0.33% of full-scale
typical,± 1% maximum
Exclusive of filters

Band start

0 to 359°
1° resolution

Band duration

1 to 360°1° resolution

Bias filter-3 dB at 0.01 Hz
1-poleLow-Pass

Not OK filter-3 dB at 2400 Hz
1-poleLow-Pass

Peak static
values-3 dB at 0.3 Hz
1-poleLow-Pass

RMS staticvalues-3 dB at 0.1 Hz
1-poleLow-Pass

Frequency Response
Bias filter-3 dB at 0.01 Hz
1-poleLow-Pass

Not OK filter-3 dB at 2400 Hz
1-poleLow-Pass

Static values

Smoothing filter
8-revolution average value

Filter Quality

Filter Quality
High-pass

4-pole80 dB per decade
24 dB per octave

Low-pass

4-pole80 dB per decade
24 dB per octave

Corner
Selection

Peak 3 dB
CornerRMS 3 dB
CornerHigh-pass

3 - 3000 Hz

10 - 3000 Hz

Low-pass

30 - 30000 Hz

40 - 30000 Hz

High-pass

4-pole80 dB per decade
24 dB per octave

Low-pass

4-pole80 dB per decade
24 dB per octave

Corner
Selection

Pk 3 dB
CornerRMS 3 dB
CornerIntegrate
3 dB Corner

High-pass

3 - 3000 Hz

10 - 3000
Hz

3-3000 Hz

Low-pass

30-30000Hz

40 - 30000
Hz40-20000
HzRecip Velocity

Accuracy

3/15

Within ± 0.33% of full-scale
typical± 1% maximum
Exclusive of filters

3500/70M Recip Impulse Velocity Monitor
Datasheet

166766 Rev. P

Low Frequency Recip Velocity

Additional accuracy
degradation occurs whenfull scale signal levels are
low:
Full Scale 0-0.5: ±3% typical
Full Scale 0-1.0: ±2% typical
Full Scale 0-2.0: ±1% typical

Velomitor

Accuracy

Within ± 0.33% of full-scale
typical± 1% maximumExclusive of filters

Velomitor

Additional accuracy
degradation occurs whenfull scale signal levels are
low:
Full Scale 0-0.5: ±3% typical
Full Scale 0-1.0: ±2% typical
Full Scale 0-2.0: ±1% typicalFrequency Response
Bias filter-3 dB at 0.01 Hz
1-poleLow-Pass

Not OK filter-3 dB at 2400 Hz
1-poleLow-Pass

Integration
filter

-3 db at 0.34 Hz
1-poleLow-Pass

Bias filter-3 dB at 0.01 Hz
1-poleLow-Pass

RMS staticvalues-3 dB at 0.1 Hz
1-poleLow-Pass

Not OK filter-3 dB at 2400 Hz
1-poleLow-Pass

Peak staticvalues-3 dB at 0.3 Hz
1-poleLow-Pass

Integration
filter

-3 db at 0.34 Hz
1-poleLow-Pass

1X & 2X Vector
FilterConstant Q filter withbandwidth = ±3% runningspeed
Q = 16.7

RMS static
values-3 dB at 0.1 Hz
1-poleLow-Pass

Peak static
values-3 dB at 0.3 Hz
1-poleLow-Pass

1X & 2X Vector
FilterConstant Q filter withbandwidth = ±3% runningspeed
Q = 16.7

Frequency Response

Filter Quality
High-pass

4-pole80 dB per decade
24 dB per octaveLow-pass

2-pole40 dB per decade
12 dB per octave

Corner
Selection

Pk 3 dB
CornerRMS 3 dB
CornerFilter Quality
High-pass

4-pole80 dB per decade
24 dB per octave

Low-pass

2-pole40 dB per decade
12 dB per octave

Integrate
3 dB Corner

High-pass

1- 400 Hz

10-400 Hz

3-400 Hz

Low-pass

40-5500
Hz

60-5500
Hz

40-5500 Hz

4/15

3500/70M Recip Impulse Velocity Monitor
Datasheet
Corner
Selection

Peak and Integrate
RMS 3 dB Corner
3 dB Corner

High-pass0.750 - 100 Hz

0.750 - 100 Hz

Low-pass

10 - 1375 Hz

15 - 1375 Hz

166766 Rev. P

AlarmsUse Rack Configuration
Software to set alert levels
for each value measured by
the monitor and danger
setpoints for any two of thevalues measured by themonitor.

Rack Space Requirements
Monitor

1 full-height front slot

I/O Modules

1 full-height rear slot

Alarm
Setpoints

Alarms are adjustable from0 to 100% of full-scale foreach measured value.
However, when the full-scale
range exceeds the range ofthe transducer, the range ofthe transducer will limit thesetpoint.

PhysicalMonitor Module (Main Board)
Dimensions(Height x Width xDepth)

241.3 mm x 24.4 mm x241.8 mm
(9.50 in x 0.96 in x 9.52 in)Weight0.91 kg (2.0 lb)

Accuracy ofalarm
setpoints

I/O Modules (non-barrier)Dimensions(Height x Width xDepth)

241.3 mm x 24.4 mm x 99.1mm(9.50 in x 0.96 in x 3.90 in)

Weight0.20 kg (0.44 lb)

Within 0.13% of the desired
value

Alarm Time Delays
You can program alarm delays using 3500
Rack Configuration Software.

I/O Modules (barrier)

Alert

From one to 60 seconds in
one second intervals

Dimensions(Height x Width xDepth)

241.3 mm x 24.4 mm x
163.1 mm
(9.50 in x 0.96 in x 6.42 in)Danger

0.1 seconds (nominal) orfrom one to 60 seconds in
one second intervals

Weight0.46 kg (1.01 lb)

Static Values
Static values are measurements used tomonitor the machine. The 3500/70M Recip
Impulse Velocity Monitor returns static values
from the following channels:

ImpulseAcceleration

5/15Direct
Bias Voltage
Six user-adjustable crankangle bands with peak or
RMS acceleration in the band

3500/70M Recip Impulse Velocity Monitor
Datasheet

Acceleration 2Direct1X Amplitude
2X Amplitude
1X Phase
2X Phase
Bias Voltage

Recip Velocity

Direct
1X Amplitude
2X Amplitude
1X Phase
2X Phase
Bias Voltage

166766 Rev. P

Seismic Barrier
CircuitParameters

Vmax (PWR) = 27.25 V
Imax (PWR) = 91.8 mA
Rmin (PWR) = 297 Ω

ChannelParameters(Entity)

Vmax = 27.25 V
Imax = 91.8 mA
Rmin (PWR) = 297 Ω

Environmental Limits

Direct
1X Amplitude
Low Frequency 2X Amplitude
Recip Velocity 1X Phase
2X Phase
Bias Voltage

OperatingTemperature

Bias voltage contains no information
about the condition of the machinery
being monitored. It is provided formonitor system diagnostics.

Barrier Parameters
The following parameters apply to CSA-NRTL/Cand CENELEC approvals.

Proximitor Barrier

CircuitParameters

Vmax (PWR) = 26.80
V (SIG) = 14.05 V
Imax (PWR) = 112.8 mA(SIG) = 2.82 mA
Rmin (PWR) = 237.6 Ω(SIG) = 4985 ΩChannelParameters(Entity)

Vmax = 28.0 V
Imax = 115.62 mA
Rmin (PWR) = 237.6 Ω(SIG) = 4985 Ω6/15

When used with Internal /External Termination
Proximitor / Seismic I/OModule:-30°C to +65°C(-22°F to +149°F)
When used with Proximitor /Seismic Internal Barrier I/O
Module (InternalTermination)
0°C to +65°C(32°F to +149°F)

Storage
Temperature-40°C to +85°C(-40°F to +185°F)

Humidity95%
Non-condensing

3500/70M Recip Impulse Velocity Monitor
Datasheet

166766 Rev. P

Hazardous Area Approvals

Compliance and Certifications

For the detailed listing of country andproduct-specific approvals, refer tothe Approvals Quick Reference Guide(108M1756).

FCC
This device complies with part 15 of theFCC Rules. Operation is subject to thefollowing two conditions:ll

For additional technicaldocumentation, please log in to
bntechsupport.com and access theBently Nevada Media Library.

This device may not cause harmfulinterference.
This device must accept any
interference received, includinginterference that may cause
undesired operation.

cNRTLus
When used with I/Omodule ordering
options without
internal barriers

EMC
European Community Directive:
EMC Directive 2014/30/EU

T4 @ Ta= -20˚C to +65˚C (-4˚F to+149˚F)
When installed per drawing
149243 or 149244.

Standards:
EN 61000-6-2; Immunity for
Industrial Environments
EN 61000-6-4; Emissions for
Industrial Environments

When used with I/Omodule ordering
options withinternal barriersElectrical Safety
European Community Directive:

Standards:
EN 61010-1

RoHS
European Community Directive:
RoHS Directive 2011/65/EU

Maritime
DNV GL rules for classification – Ships,
offshore units, and high speed and lightcraft
ABS Rules for Condition of Classification,
Part 1lClass I, Zone 2: AEx/Ex nA nC ic[ia Ga] IIC T4 Gc;
Class I, Zone 2: AEx/Ex ec nC ic [iaGa] IIC T4 Gc;
Class I, Division 2, Groups A, B, C,and D (W/ IS Output for Division1)
T4 @ Ta= -20˚C to +65˚C (-4˚F to+149˚F)
When installed per drawing
138547.

LV Directive 2014/35/EUl

Class I, Zone 2: AEx/Ex nA nC ic IIC
T4 Gc;Class I, Zone 2: AEx/Ex ec nC ic IIC
T4 Gc;Class I, Division 2, Groups A, B, C,and D;

Steel Vessels Rules
Offshore Units and Structures

7/15

3500/70M Recip Impulse Velocity Monitor
Datasheet

166766 Rev. P

ATEX/IECEx
When used with I/Omodule ordering
options without
internal barriers

II 3 GEx nA nC ic IIC T4 Gc;
Ex ec nC ic IIC T4 Gc;
T4 @ Ta= -20˚C to +65˚C (-4˚F to+149˚F)
When installed per drawing
149243 or 149244.

When used with I/Omodule ordering
options withinternal barriers

II 3(1) G
Ex nA nC ic [ia Ga] IIC T4 Gc;
Ex ec nC ic [ia Ga] IIC T4 Gc;
T4 @ Ta= -20˚C to +65˚C (-4˚F to+149˚F)
When installed per drawing
138547.

8/15

3500/70M Recip Impulse Velocity Monitor
Datasheet

166766 Rev. P

Ordering Information

Ordering Considerationslll

For the detailed listing of country andproduct-specific approvals, refer tothe Approvals Quick Reference Guide(108M1756).

For I/O modules with ExternalTerminations, order the External
Termination Blocks and cable separatelyfor each I/O module.
For the Internal Barriers, refer to the 3500
Internal Barrier datasheet, document
141495.
External Termination Blocks cannot be
used with Internal Termination I/O
Modules.

For additional technicaldocumentation, please log in to
bntechsupport.com and access theBently Nevada Media Library.

Recip Impulse / Velocity Monitor
3500/70M - AA-BB

The lower limit for machine speed is
60 RPM in standard product. For
machine speeds down to 30 RPM,
modification 135M8137-01 is required.

A: I/O Module Type

Software Compatibility
3500/01
Configuration
SoftwareVersion 5.2 or later

3500/02 Data
Acquisition
SoftwareVersion 2.50 or later

3500/03
Operator
Display
SoftwareVersion 1.50 or later

System1
SoftwareVersion 6.90 or later

01

Prox/Velom I/O Module with Internal
Terminations

02

Prox/Velom I/O Module with External
Terminations

03

Internal Barrier, Four Accelerometers

04

Internal Barrier, Two Accelerometers,
Two Velomitors

05

Internal Barrier, Four Velomitors

B: Agency Approval00

None01cNRTLus (Class 1, Division 2)

02

ATEX/ IECEx/ CSA (Class 1, Zone 2)
Order the Earthing Module for eachrack with internal barriers.

Firmware Compatibility
3500/70M
FirmwareVersion 4.21 or later

3500/22M TDIFirmware

Version 1.75 or later

3500/22M USB
TDI Firmware

External Termination Blocks
Part Number
128702-01

Version 4.05 or later

9/15

Description
Recorder External
Termination BlockEuro Style connectors

3500/70M Recip Impulse Velocity Monitor
DatasheetPart Number

166766 Rev. P

Description

128710-01

Recorder External
Termination Block
Terminal Strip connectors

125808-08

Proximitor / Velomitor
External Termination BlockEuro Style connectors

128015-08

Proximitor / Velomitor
External Termination Block
Terminal Strip connectors

0007

7 feet (2.1 meters)

0010

10 feet (3.0 meters)

0025

25 feet (7.6 meters)

0050

50 feet (15.2 meters)

0100

100 feet (30.5 meters)

B: Assembly Instructions
01

Not assembled

02

Assembled

CablesSpares3500 Transducer (XDCR) to External
Termination (ET) Block Cable

Part Number

129525 - AAAA-BB

Description

176449-09

3500/70M Recip Impulse
Velocity Monitor

166226-01

3500/70M Recip Impulse
Velocity Monitor User
Manual135489-01

I/O Module with Internal
Barriers, Internal
Terminations
4 x Prox/Accel

135489-02

I/O Module with Internal
Barriers, Internal
Terminations
2 x Prox/Accel and2 x Velomitor

135489-03

3500 Recorder Output to External
Termination (ET) Block Cable

I/O Module with Internal
Barriers, Internal
Terminations
4 x Velomitor

140471-01

Prox/Velom I/O Module withInternal Terminations

129529-AAAA-BB

140482-01

Prox/Velom I/O Module with
External Terminations

00561941

3500/70M Prox/Velom I/O
Module ten-pin connector
shunt

A: I/O Cable Length00055 feet (1.5 meters)

0007

7 feet (2.1 meters)

0010

10 feet (3.0 meters)

0025

25 feet (7.6 meters)

0050

50 feet (15.2 meters)

0100

100 feet (30.5 meters)

B: Assembly Instructions
01

Not assembled

02

Assembled

A: I/O Cable Length0005

5 feet (1.5 meters)

10/15

3500/70M Recip Impulse Velocity Monitor
DatasheetPart Number

166766 Rev. P

Description

00580434

Internal I/O Moduleconnector header
Euro Style, 8 pin
For I/O modules 128229-01
and 138708-01

00580432

Internal I/O Moduleconnector header
Euro Style, 10 pin
For I/O modules 128229-01,
138708-01

00502133

Internal I/O Moduleconnector header
Euro Style, 12 pin

166M2389

Connector header
Push-in-spring type
(Alternative for PN00580434)

166M2388

Connector header
Push-in-spring type
(Alternative for PN00580432)

11/15

3500/70M Recip Impulse Velocity Monitor
Datasheet

166766 Rev. P

Graphs and Figures

1. Status LEDs
2. Buffered Transducer Outputs
3. Prox/Velom I/O Module, Internal Termination, 140471-01
4. Prox/Velom I/O Module, External Termination, 140482-01
Figure 1: 3500/70M Front and Rear Views

12/15

3500/70M Recip Impulse Velocity Monitor
Datasheet

166766 Rev. P

The I/O modules with internal or external terminations have the same jumpers.
Figure 2: Side View of I/O Modules

13/15

3500/70M Recip Impulse Velocity Monitor
Datasheet

166766 Rev. P

1. Barrier I/O module to connect four Accelerometer
sensors, 135489-01
2. Barrier I/O module to connect two Accelerometer
sensors and two Velomitor sensors, 135489-02
3. Barrier I/O module to connect four Velomitor sensors,
135489-03
Figure 3: Barrier I/O Modules

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3500/70M Recip Impulse Velocity Monitor
Datasheet

166766 Rev. P

Copyright 2024 Baker Hughes Company. All rights reserved.

Bently Nevada, M2, Proximitor, Velomitor and Orbit Logo are registered trademarks of Bently Nevada, a Baker Hughes
business, in the United States and other countries. The Baker Hughes logo is a trademark of Baker Hughes Company.
All other product and company names are trademarks of their respective holders. Use of the trademarks does not
imply any affiliation with or endorsement by the respective holders.
Baker Hughes provides this information on an “as is” basis for general information purposes. Baker Hughes does notmake any representation as to the accuracy or completeness of the information and makes no warranties of any
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for a particular purpose or use. Baker Hughes hereby disclaims any and all liability for any direct, indirect,
consequential or special damages, claims for lost profits, or third party claims arising from the use of theinformation, whether a claim is asserted in contract, tort, or otherwise. Baker Hughes reserves the right to makechanges in specifications and features shown herein, or discontinue the product described at any time without
notice or obligation. Contact your Baker Hughes representative for the most current information.
The information contained in this document is the property of Baker Hughes and its affiliates; and is subject tochange without prior notice. It is being supplied as a service to our customers and may not be altered or its content
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1631 Bently Parkway South, Minden, Nevada USA 89423
Phone: 1.775.782.3611 (US) or Bently.com/support
Bently.com

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