Bently Nevada 990 Specifications

990 Vibration Transmitter

Datasheet

Bently Nevada Machinery Condition Monitoring

Description

The 990 Vibration Transmitter is intended primarily for the
original equipment manufacturers (OEMs) of centrifugal air
compressors or small pumps, motors, or fans who prefer to
provide a simple 4 to 20 mA proportional vibration signal as
the input to their machinery control system.

The transmitter is a two-wire, loop-powered device that
accepts input from our 3300 NSv proximity probe and its
matching extension cable (available in 5 m and 7 m system
length options).

The transmitter conditions the signal into appropriate peak­to-peak vibration amplitude engineering units, and provides
this value as a proportional 4 to 20 mA industry-standard
signal as the input to the control system where machinery
protection alarming and logic occurs†.

The 990 transmitter provides the following notable features:

141612 Rev. P

l Integrated Proximitor Sensor requires no external unit

l Non-isolated “PROX OUT" and "COM" terminals plus a

coaxial connector to provide a dynamic vibration and
gap voltage signal output for diagnostics‡.

l Non-interacting zero and span potentiometers under

the Transmitter label supports loop adjustment.

l Test Input pin for quick verification of loop signal output,

using a function generator as the input.

l A Not OK/Signal Defeat circuit prevents high outputs or

false alarms due to a faulty proximity probe or loose
connection.

l Choice of DIN-rail clips or bulkhead mounting screws as

standard options simplifies mounting.

990 Vibration Transmitter
Datasheet 141612 Rev. P

l Potted construction for high humidity

(up to 100% condensing) environments.
Compatibility with 3300 NSv proximity
probe allows transducer installation in
small areas with minimal clearance,

conventions for signal polarity. We strongly
recommend the use of this test adapter for all
applications to maintain isolation between test
equipment and the loop signal, and ensure
that the installation maintains machinery
protection integrity.

typical of centrifugal air compressors.

Specifications

Channels configured for Velocity or
Acceleration can provide, Direct, 1X
amplitude/phase and 2X
amplitude/phase.

Notes

†

Vibration transmitters have many limitations
when compared to a continuous vibration
monitoring system. They are a practical
solution in some applications for measuring
general vibration levels and are a valuable tool
for overall vibration trending. However, they
provide limited capability for machinery
diagnostics using the vibration signal and do
not capture dynamic vibration signals (used
for diagnostics) in the event of a vibration
alarm. While the transmitter is capable of peak
vibration alarming and non-OK checking, the
4-20 mA signal cannot be used to determine
the phase of vibration, and monitor functions
such as gap alarms, phase alarms, Timed OK
channel defeat, Danger Bypass, and Trip
Multiply cannot be used. In addition, PLCs
attached to the vibration transmitter can only
provide peak-to-peak trending data and are
not suitable for plant-wide diagnostic systems
such as System 1 or Rule Paks.

‡

The 990 Vibration Transmitter's "Prox Out"
coaxial connector provides a non-isolated
dynamic transducer signal for machinery
diagnostics. You can connect this signal
directly to battery-powered or isolated test
equipment to diagnose machinery problems.
However, since the "PROX OUT" signal is not
isolated from the 4 to 20 mA loop signal, an
interface is available (and strongly
recommended) for signal isolation. The 990/991
Test Adapter conditions the 990 Transmitter's
"PROX OUT" signal for use with ac-powered test
equipment. It also inverts and isolates the 990's
transducer signal, making it suitable for
equipment such as oscilloscopes and
analyzers, and preserving industry-standard

Unless otherwise noted, the following
specifications apply at +22 °C (+72 °F) using a
3300 NSv Probe and Extension Cable, and an
AISI 4140 steel target.

These specifications also apply to 990
with modifications 147202-01 (RMOD 4140
3300XL 8MM 5M) and 165335-01 (MOD
4140 3300 XL 8MM 9M).

Electrical

Input

Power

4 to 20 mA
signal
output

4 to 20 mA
loop
accuracy

Probe gap

Maximum
loop
resistance

Current
limiting

Zero and
span

NOT
OK/signal
defeat

Power-up
inhibit

Accepts 1 non-contacting 3300 NSv
Proximity Probe and extension cable.

Requires +12 to +35 Vdc input at the
transmitter terminal.

4 to 20 mAdc over specified full-scale
range in 2-wire configuration.

Within ±1.5% over specified full-scale
range. Accuracy is rated from the TEST
signal input to the voltage measured
across a 250 Ω loop resistance.

Probe must be gapped between 0.5
and 1.75 mm (20 and 55 mils) from
target to ensure full scale range.

1,000 Ω including cable at 35 Vdc.

23 mA typical.

Non-interacting external adjustments.

Signal output will go to less than 3.6
mA within 100 µs after a Not OK
condition occurs. Signal output is
restored within 2-3 seconds after the
Not OK condition is removed.

Signal output stays at less than 3.6
mA (NOT O.K.) for 2 to 3 seconds after
power is applied. The purpose is to
signal that the device is not yet ready.
Transients may be observed when
device goes O.K.

2/15

990 Vibration Transmitter
Datasheet 141612 Rev. P

Proximitor
sensor
output

Output
impedance

Prox out
linear range

Prox Out
incremental
scale factor

Temperature
stability

Frequency
response

Minimum
target size

Leadwire
length

Non­Hazardous,
Zone 2 or Div
2 Hazardous
area
locations

Intrinsically
Safe
Hazardous
area
locations

Compatible with ungrounded,
portable test equipment. When using
grounded, ac-powered test
equipment, use the 122115-01 Test
Adapter for signal isolation.

Prox Out has a 10 kΩ output
impedance calibrated for a 10 MΩ
load.

1.4 mm (55 mils). Begins at
approximately 0.25 mm (10 mils) from
target surface.

7.87 mV/µm (200 mV/mil) ± 6.5%
typical including interchangeability
errors when measured in increments
of 0.25 mm (10 mils) over the linear
range using a flat 30 mm (1.2 inch)
target. Worst case 7.87 mV/µm ± 10%.
Typical Noise Level: 50 mV/pp.

Incremental scale factor remains
within ±10% of 7.87 mV/µm (200
mV/mil) from 0 °C to +70 °C (+32 °F to
+158 °F).

5 Hz to 6,000 Hz +0, -3 dB.

9.5 mm (0.375 in) diameter.

Maximum for Proximitor Sensor
Output (BNC connector), maximum
cable distance is 3 metres (10 feet).

Power Supply: 28V

Zone 0/1

Terminal
Terminal
blocks E1­E2 “power
supply 4­20 mA”

Ui [28 V Uo[28 V Uo[ 28 V

Ii [120 mA Io [6 mA

Pi[ 0.84 W

Ci [20 nF Co [ 80 nF

Li [10 μH Lo [1H Lo [5.3 mH

blocks E3-

E4 and

connector

J2

"Proximitor"

Po [ 0.17

W

Connector
J3 "Probe"

Io [ 100
mA

Po [ 0.8 W

Co[ 27.3
nF

General Purpose Approval by

Electrical
classification

Canadian Standards Association
(CSA/NRTL/C) in North America and
by VDE in Europe. 990 has the CE
mark for Europe

Maritime Approvals

American Bureau of
Shipping (ABS) Type
Approval

Certification Number: 06­HS177078-3-PDA

Environmental Limits

Transmitter Temperature

Operating
temperature

Storage
temperature

Probe Temperature

Operating
temperature

Storage
temperature

Relative
humidity

-35 °C to +85 °C (-31 °F to +185 °F)

-51 °C to +100 °C (-60 °F to +212 °F).

-35 °C to +177 °C (-31 °F to +350 °F).

-51 °C to +177 °C (-60 °F to +350 °F).

100% condensing, non-submerged,
with protection of coaxial
connectors.

Mechanical

Transducer
tip material

Transducer
case material

Probe Cable

Cable armor
(optional)

Tensile
strength

Transmitter
weight

Total system
weight

Polyphenylene sulfide (PPS).

AISI 303 or 304 Stainless Steel (SST).

75Ω coaxial, fluoroethylene
propylene (FEP) insulated.

Flexible AISI 302 SST with optional FEP
outer jacket.

222 N (50 lbf) probe case to probe
lead, maximum.

0.43 kg (0.9 lbm).

0.82 kg (1.8 lbm) typical.

3/15

990 Vibration Transmitter
Datasheet 141612 Rev. P

Compliance and Certifications

FCC

This device complies with part 15 of the
FCC Rules. Operation is subject to the
following two conditions:

l This device may not cause harmful

interference.

l This device must accept any

interference received, including
interference that may cause
undesired operation.

EMC

EN 61000-6-2

EN 61000-6-4

EMC Directive 2014/30/EU

ATEX

ATEX Directive 2014/34/EU

RoHS

RoHS Directive 2011/65/EU

Maritime

ABS 2009 Steel Vessels Rules

1-1-4/7.7,4-8-3/1.11.1,4-9-7/13



4/15

990 Vibration Transmitter
Datasheet 141612 Rev. P

Hazardous Area Approvals

For the detailed listing of country and product
specific approvals, refer to the Approvals Quick
Reference Guide (108M1756) available from

Bently.com.

CSA/NRTL/C

Class I, Div 2
Groups A, B, C, D

T5@ Ta [+85°C, Type 4

Installed per Drawing 128838

ATEX/IECEx

II 1 G

Ex ia IIC T4 Ga

T4 @ Ta = -35°C to +85°C

II 3 G

Ex nA IIC T4 Gc
T4 @ Ta= -35 ˚C to + 85˚C



Entity Parameters

Zone 2

Power Supply: 28V

Zone 0/1

Terminal blocks
E1-E2 “power
supply 4-20
mA”

Ui [28 V Uo[28 V Uo[ 28 V
Ii [120 mA Io [6 mA Io [ 100 mA
Pi[ 0.84 W Po [ 0.17 W Po [ 0.8 W
Ci [20 nF Co [ 80 nF Co[ 27.3 nF
Li [10 μH Lo [1H Lo [5.3 mH

Terminal blocks
E3-E4 and
connector J2
"Proximitor"

Connector J3
"Probe"

5/15