Danfoss DHP-AL Installation And Service Instructions Manual page 45

Problem – Alarm MS (motor protection)
Cause
1. Phase drop or blown fuse.
2. Defective soft-starter.
3. Defective contactor.
4. Defective or incorrectly set motor protec-
tion.
5. Cable break.
6. Defective compressor.
Problem – Alarm sensor (all)
Cause
Sensor fault alternatively cable fault.
Troubleshooting
Check that all phases are present on the
terminal block for incoming supply. If not,
check the fuses in the cabinet.
Also check that all wiring is secure, if screw
terminals are used they must be properly
tightened, if phoenix flat spring terminals
are used, the cables must be secure in the
correct hole with load on the cable.
Measurement check and establish that
when the control computer gives a signal
(there must be voltage between A1 & A2 on
the soft-starter), the soft-starter releases all
three phases down to the compressor.
Measurement check and establish that
when the control computer gives a signal
(there must be voltage between A1 & A2
on the contactor), the contactor releases all
three phases down to the compressor.
Use a hook-on meter to establish when the
motor protection deploys, check what the
motor protection is set to. Compare with
the table.
Check the supply to the motor protection//
soft-starter/compressor.
Measurement check the three phases (each
to zero) at the compressor. Deviations from
the average of the three values must not
be more than 12% on any of the phases.
If measurement checking the winding's
impedance the same value must be on all
three windings.
Troubleshooting
• When reading the resistance of the sen-
sors, the sensor leads must first be discon-
nected from the control equipment or
terminal block.
• First take a reading from the sensor includ-
ing cable and check against the ohm table
in the "Measurement points" section.
• If the read off value does not correspond
with the table, only measure the sensor and
check the ohm table in the "Measurement
points" section.
VMBME102
Remedy
If any of the phases are not present, check
backwards towards the building's main
electrical cabinet. If there are no phases
there, contact the network supplier.
If the soft-starter does not release the phas-
es when it receives signals from the control
computer, replace it.
If the contactor does not release the phases
when it receives signals from the control
computer, replace it.
If the motor protection is defective, replace
it.
If incorrectly set, adjust to the correct value.
If a cable is damaged, replace it.
If the compressor is defective, replace it.
Remedy
If the sensor gives a correct value, the cable
is defective.
If the sensor does not give a correct value,
the sensor is defective.
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