MCD 200 Series
16
MG.17.D3.02 – VLT is a registered Danfoss trademark
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MCD 202 Start Performance Test
This procedure tests for correct operation of the MCD
202 during start. Start mode is indicated by a flashing
Run LED (Green). This test is performed using an AC
ammeter (clip on or similar).
Test:
•
Calculate the expected motor start current by
multiplying the
MCD 202 current rating
by the
Motor FLC
setting
(Motor FLC pot) and the
Current Limit setting
(Current Limit pot).
•
Initiate a start and measure the actual motor start
current on phase 1 (L1/T1) and phase 3 (L3/T3).
Action:
1. If the measured start current is as expected
and motor starting problems are still
experienced:
The cause of the motor starting problem is not the
MCD 202. Check the MCD 202 settings are
appropriate and look for outside causes to the
problem.
2. If the start current is not as expected:
The SCR may have failed. Perform the Power Circuit
Test described later in this section.
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.
Run Performance Test
MCD 200 soft starter incorporate internal bypass
contactors. This procedure tests the operation of the
internal bypass contactors. If the internal bypass
contactor does not operate, SCRs will eventually fail
due to thermal stress. This test is performed using an
AC voltage meter.
Test:
•
While the MCD 200 is in the Off mode, measure
the voltage across each controlled phase (L1 to
T1 and L3 to T3). Line voltage should be
measured.
•
Start the soft starter and listen for the bypass relay
closing. This should occur when the Run LED
(Green) changes state from flashing to on.
•
Measure the voltage across each controlled phase
(L1 to T1 and L3 to T3). This should be less than
0.5 V AC.
•
When a stop command is given, listen for the
bypass relay opening. If soft stop is being used,
this should occur when the Run LED (Green)
changes state from on to flashing. If no soft stop
is being used, this should occur when the Run
LED (Green) changes state from on to off.
Action:
1. If the line voltage is not measured across the
MCD 200 when in the off mode:
The Bypass Contactor is likely to be damaged and
should be replaced.
ATTENTION
The Bypass Contactors used in the MCD 200
are latching. The MCD 200 control circuits are
designed to open the Bypass Contactors even in the
event of removal or loss of control voltage. However it
is still possible that the Bypass Contactor may be
closed when there is no control supply to the MCD
200. On application of control voltage the MCD 200
will open the Bypass Contactors.
2. If Bypass Relay does not operate:
The Bypass Contactor, Main Control PCB, Interface
PCB or connection between these items may be
faulty.
•
Verify plug connections between the Main
Control Module, Interface PCB and Bypass Relay
using the following method.
-
Unplug the Main Control PCB from the
Interface PCB.
-
Unplug the Interface PCB from the Bypass
Contactors.
