Danfoss DHP-A Service Instructions Manual page 13

Service instructions
Problem – Alarm MS (motor protection)
Cause
1. Phase drop or blown fuse.
2. Defective soft-starter (three-
phase heat pump).
3. Defective soft-starter (single
phase heat pump).
4. Defective or incorrectly set motor
protection.
5. Cable break.
6. Defective compressor (applies to
3-phase heat pumps).
7. Alarm from the overload protec-
tion on the brine pump (only cer-
tain heat pump models).
8. Alarm from single phase soft
starter.
Problem – Alarm sensor (all)
Cause
Sensor fault alternatively cable
fault.
Danfoss Heating Solutions
Domestic heat pumps
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 termi-
nals 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
I/O card gives a signal (there must be voltage be-
tween A1 & A2 on the soft-starter), the soft-starter
releases all three phases down to the compressor.
Check measure and establish that when the I/O
card gives a signal (there must be voltage between
ON and N on the soft-starter), the soft-starter relea-
ses the phases to the compressor.
Use a hook-on metre to establish when the motor
protection deploys, check what the motor protec-
tion is set to. Compare with the table. For three
phase heat pumps all three phases must be sup-
plied.
Check the supply to the motor protection, soft-
starter or compressor.
Measurement check the voltage on the three pha-
ses (each to zero) at the compressor. There must
not be any large deviation between the phases. If
measurement checking the winding's resistance
the same value must be on all three windings.
Switch the heat pump off and on. If the alarm re-
mains check the WSK switch in the brine pump.
Check the fault cause using the soft start LEDs.
Troubleshooting
▪ When reading the resistance of the sensors,
the sensor leads must first be disconnected
from the control equipment or terminal block.
▪ First take a reading from the sensor including
cable and check against the ohm table, see
chapter Measurement points.
▪ If the read off value does not correspond with
the table, only measure the sensor and check
the ohm table, see chapter Measurement
points.
Remedy
If any of the phases are missing, 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 pha-
ses when it receives signals from the I/O
card, replace it.
If the soft-starter does not release the pha-
ses when it receives signals from the I/O
card and does not alarm as below, 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.
If the brine pump 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.
VIGFI102
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