Bently Nevada 3500/77M Data sheet
3500/77M Recip Cylinder Pressure
Monitor
Datasheet
Bently Nevada Machinery Condition Monitoring
Description
The 3500/77M Recip Cylinder Pressure Monitor is a 4-channel
monitor that accepts input from Bently Nevada approved
pressure transducers, conditions the signal to make various
pressure measurements for reciprocating compressors, and
compares the conditioned signals with user-programmable
alarms.
The primary purpose of the 3500/77M monitor is to provide:
l Machinery protection by continuously comparing
monitored parameters against configured alarm
setpoints to drive alarms.
l Essential machine information for operations and
maintenance personnel.
Depending on configuration, each channel typically
conditions its input signal to provide various parameters
called measured variables. Users can configure Alert
setpoints for each active measured variable and Danger
setpoints for any two of the active measured variables.
147485 Rev. R
Each channel of the 3500/77M will provide eight measured
variable values that relate to cylinder pressure operation. The
five values that relate to a single chamber are as follows:
l Discharge Pressure
l Suction Pressure
l Maximum Pressure
l Minimum Pressure
l Compression Ratio
3500/77M Recip Cylinder Pressure Monitor
Datasheet 147485 Rev. R
Three measured variables combine one or
more channel values with configured
mechanical parameters to compute their
value:
l Peak Rod Compression
l Peak Rod Tension
l Degree of Rod Reversal
For more information on the 3500/77M Recip
Cylinder Pressure Monitor, refer to the User
Guide (document 146282).
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3500/77M Recip Cylinder Pressure Monitor
Datasheet 147485 Rev. R
Specifications
Inputs
Accepts 1 to 4 channels of Bently
Signal
Scale Factor
range† 95,000 mV/psi for 100 psia
range† 38,000 mV/psi for 250 psia
range† 19,000 mV/psi for 500 psia
range† 9,500 mV/psi for 1000 psia
range† 3,800 mV/psi for 2500 psia
range† 1,900 mV/psi for 5000 psia
range† 950 mV/psi for 10,000 psia
†All pressure transducers will be
supplied with scale factor specifications
that include pressure/voltage values at
two points. The above data assumes
+0.5 Vdc at 0 psia and +10.0 Vdc at the
full-range psia value.
Nevada approved positive voltage
3rd-party pressure transducers
(psia)
Power
Consumption
7.8 watts with transducer supplies at
full load.
Outputs
Front Panel LEDs
OK LED
TX/RX LED
Bypass LED
Buffered Transducer
Outputs
The Buffered Transducer Outputs on
monitors using the Cylinder Pressure I/O
module will be inverted and offset by -
2.265 Vdc.
Output Impedance 550 Ω
Transducer Power
Supply
Indicates when the 3500/77M
is operating properly.
Indicates when the 3500/77M
is communicating with other
modules in the 3500 rack.
Indicates when the 3500/77M
is in Bypass Mode.
The front of each monitor has
one coaxial connector for
each channel. Each connector
is short-circuit protected.
+23.0 ± 0.8 Vdc with 24.5 ma
current limiting on each
channel.
Signal Conditioning
Frequency
Response
Pressure
Accuracy
0 to 5.5 kHz on all configured
pressure channels
Within ± 0.5% of pressure transducer
full-range (9.5 volts: From +0.5 to
+10.0 volts) @ +25°C (77º F)
Within ± 1.0% of pressure transducer
full-range (9.5 volts: From +0.5 to
+10.0 volts) over –30 °C to +65 °C (22 ºF to 150 ºF)
Measured Variables
Discharge Pressure, Suction Pressure,
Cylinder
Pressure
Input Impedance
Internal/
External
Termination
Cylinder
Pressure I/O
Maximum Pressure, Minimum
Pressure, Compression Ratio, Peak
Rod Compression, Peak Rod Tension,
Degree of Rod Reversal
50 kΩ
Environmental Limits
Operating Temperature
When used with
Internal/External
Termination Cylinder
Pressure I/O Module:
Storage Temperature
Humidity 95%, non-condensing
-30 °C to +65 °C
(-22 °F to +150 °F)
-40 °C to +85 °C
(-40 °F to +185 °F)
Physical
Monitor Module
Dimensions (Height x
Width x Depth)
Weight 0.91 kg (2.0 lb.)
I/O Modules
Dimensions (Height x
Width x Depth)
241.3 mm x 24.4 mm x 241.8
mm
(9.50 in x 0.96 in x 9.52 in)
241.3 mm x 24.4 mm x 99.1
mm
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