Danfoss VLT Series Service Manual page 15

9)
Symptom
No information in display
12)
Disconnect all control signal
plugs on the control card.
Does the fault disappear?
14)
Is the DC Bus voltage OK? Should read 1.4 x the AC line V.
Measure the DC Bus voltage between terminal +VDC and –VDC.
– +
Resume operation
10)
Is the correct line voltage
present on the input terminals?
L1/R (91), L2/S (92), L3/T (93)
YES
NO YES
Also refer to pages 3-1 and 3-2.
– +
16)
Replace the Interface/
ILD Card.
Does the fault disappear?
YES
NO
YES NO
17)
Replace the Control Card.
Does the fault disappear?
NO
Replace the
Relay Card
Section Two
11)
Check Input Disconnect
and fusing.
If fuses are blown, check
for a short circuit in the
Power Section.
13)
The fault may be caused
by a short circuit in the
control signals.
Check control wiring for
proper connection.
15)
Test the soft charge
circuit, input rectifier,
and DC Bus capacitors.
NO YES
Resume operation
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