Connections - SKF On-line System WVT User Manual

Hardware Overview

Connections

Connections
Analog Sensor Input Connections
The SKF Multilog WVT has four input channel pairs, making a total of eight input
channels. The four input channel pairs are identical and comprise one dynamic input for
vibration and one static (or process) input for temperature. The unit is designed to work
with the CMSS 2350T-D2 sensor. This is a four-wire device comprising power, analog
vibration signal, temperature and ground as detailed in the table below.
Analog Input Channel Pair Connections
Pin
+
S
T
–
The four input channel pairs are labeled CH1, CH2, CH3 and CH4. The orange
connector on each can be removed to make wire termination easier.
It is not necessary to connect the temperature input if it is not needed. Note that there
is no cable shield grounding inside the SKF Multilog WVT. The shield of the CMSS 2350
sensor cable, CMAC 2350-CABLE-xxM (xxM indicates the cable length in meters), is
grounded at the sensor side.
Any unused glands must be removed and replaced with the blanking plugs provided,
tightened to 4 N-m (35 lb.-in.) torque to maintain the IP rating.
Analog Input Electrical Details
The sensor is powered by 3.3 VDC power from the board relative to common. Power
can be turned on and off to each sensor to conserve battery power. The signal returned
from the sensor swings around a 1.5 V mid-point with a range of ±1.25 V. So the total
input range is 0.25 to 2.75 V. Therefore, for a nominal 50 mV/g sensor, the overall
range is ±25 g (or 25 g peak).
The bias voltage point of 1.5 V is monitored by the unit and an alert is generated to the
system if it goes out of range. The bias voltage may vary based on temperature.
Measurements are multiplexed to the on-board 16-bit analog-to-digital converter.
There is an additional hardware demodulator (or enveloper) for bearing condition
measurement. Dynamic signals pass through various gain, filtering and anti-alias
stages, whereas the static signals pass directly to the analog-to-digital converter.
The scaling of the static temperature inputs is assumed to be –10.9 mV/°C giving an
overall sensitivity range of –50 to +150 °C (–58 to +302 °F).
2 - 8
Function
Sensor supply (+ve) (red wire)
Analog signal input (white wire)
Temperature input (green wire)
Common (black wire)
Notes
Nominal +3.3 VDC (max current 100 μA)
Input range 0 to 3 V
Input range 0 to 3 V
Sensor common
SKF Multilog On-line System WVT
User Manual