MCD 200 Series
MG.17.D3.02 – VLT is a registered Danfoss trademark
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Tests
The following tests and measurements can be used to
verify soft starter condition and operation.
MCD 201 Start Performance Test
This procedure tests for correct operation of the MCD
201 during start. Start mode is indicated by a flashing
Run LED (Green). This test is performed using an AC
voltage meter.
Test:
•
Before commanding the MCD 201 to start,
measure the voltage across each controlled phase
(L1-T1 and L3-T3). This should be close to the
system line voltage.
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When the MCD 201 is commanded to start,
measure the voltage across each controlled phase
(L1-T1 and L3-T3). This voltage should start close
to the system line voltage and ramp down to less
than 2VAC just before the MCD 201 reaches Run
mode.
Action:
1. If measurement shows voltage across the SCR
to be equivalent to line voltage before start,
dropping to <2 VAC at run, and motor starting
problems are still experienced:
The cause of the motor starting problem is not the
MCD 201. Look for outside causes to the problem.
2. If zero voltage is measured across the SCR
before, or at the commencement of a start:
The SCR may have failed. Perform the Power Circuit
Test described later in this section.
3. If the voltage across the SCR remains at
system line voltage:
This indicates that the SCR on that phase is not firing.
The Main Control PCB, Interface PCB or connection
between them items may be faulty.
•
Verify plug connections between the Main
Control PCB and Interface PCB by
- Removing and refitting the Main Control PCB
- Check for correct operation.
•
If correct operation is not restored
- Replace the Main Control PCB
- Check for correct operation.
•
If correct operation is not restored
- Refit the original Main Control PCB.
- Replace the Interface PCB.
- Check for correct operation.
•
If correct operation is still not restored
- Replace both the Main Control PCB and the
Interface PCB.
