Bench testing a CMCP420VT(T) is quite easy and
can be accomplished using a 24 VDC power supply and a DVM (Digital Volt
Meter) in mA (Amp) mode. Be sure that the fuse in the mA input of your
DVM is good. Most quality DVM’s have a 1 and 10 Amp selection. Select
the lowest as you will only be measuring to about 30 mA or 0.030 Amp.
Be sure the power supply is wired plus to plus and minus to minus to
the CMCP420VT. The DVM can be inserted in series in either leg.
***** Important *****
The CMCP420VT requires
a minimum voltage dependant on resistance in the loop. If units locks
at >21 mA voltage needs to be increased by using an external +24 VDC
power supply.
In the case of the CMCP420VT-T with Temperature
the loop mA is checked the same way, just move the wires to the temperature
side of the terminal. Heat the unit gently with a heat gun or your hand
and mA output will increase. Allow time for unit to heat soak and do
not overheat.
The CMCP420VT will begin operation as soon as
24 VDC power is supplied. Start up time is short but give the unit about
30 seconds for the integrator to settle. At rest on a table or desk
top the unit should read about 4.0 mA (0.004 Amp) depending on floor
and table vibration. Tap the unit gently against the table at a rate
of a couple times per second. Increasing the force of the taps will
cause the unit to read over 20 mA (0.020 Amps).
Problem |
Solution |
No Output |
Verify Wiring
Verify Supply Voltage at V+ Terminal (18
to 36 VDC)
Verify Loop with DVM in Series (mA Mode)
Verify
PLC/DCS Scaling (4 mA = 0, 20 mA =1.00)
Verify External Power
Supply Common is Established (If Used)
Replace with Spare |
Output Locked at >21 mA |
Inadequate Supply Voltage
Verify Supply Voltage at V+
Terminal (18 to 36 VDC)
Increase Supply Voltage as Required |
Low Vibration Reading |
Verify with Portable Meter
Verify PLC/DCS Scaling (4 mA
= 0, mA =1.00)
Verify Sensor is Correctly Positioned on Bearing |
High Vibration Reading |
Verify with Portable Meter
Verify PLC/DCS Scaling (4 mA
= 0,20 mA =1.00)
Repair Machine or Adjust Process |
Erratic Measurement |
Verify with Portable Meter
Verify Unit is Mounted Securely
Verify Wiring and Intermediate Terminals |
|
