Initial Start Up Or After Repair Drive Tests - Danfoss VLT HVAC Drive FC 100 Service Manual

High Power Service Manual for VLT
Adjustable Frequency Drives
Verify the reference voltage power supply is correct as follows.
1. With a voltmeter, measure the voltage at control card terminal 50 with respect to terminal
55. The meter should read between 9.2 and 11.2 VDC.
If the 10 V supply voltage is not present, conduct the Control Card Voltage Test earlier in this
section.
If the 10 volts is present proceed with checking the individual inputs as follows.
2. Connect the (-) negative meter lead to reference terminal 55.
3. Connect the (+) positive meter lead to desired terminal 53 or 54.
For analog input terminals 53 and 54, a DC voltage between 0 and +10 VDC should be read to
match the analog signal being sent to the adjustable frequency drive. Or a reading of 0.9 to 4.8
VDC corresponds to a 4 to 20 mA signal
Note that a (-) minus sign preceding any reading above indicates a reversed polarity. In this case,
reverse the wiring to the analog terminals.

6.4 Initial Start Up or After Repair Drive Tests

Following any repair to an adjustable frequency drive or testing of an adjustable frequency drive
suspected of being faulty, the following procedure must be followed to ensure that all circuitry in
the adjustable frequency drive is functioning properly before putting the unit into operation.
1. Perform visual inspection procedures as described in Table 4-1.
2. Perform static test procedures 6.2.1, 6.2.2 and 6.2.5 for D-frame size units or 6.2.3, 6.2.4
and 6.2.5 for E-frame size units to ensure the adjustable frequency drive is safe to start.
3. Disconnect the motor leads from the output terminals (U, V, W) of the adjustable fre-
quency drive.
4. Apply AC power to the adjustable frequency drive.
5. Give the adjustable frequency drive a run command and slowly increase the reference
(speed command) to approximately 40 Hz.
6. Using an analog voltmeter or a DVM capable of measuring true RMS, measure phase-to-
phase output voltage on all three phases: U to V, U to W, V to W. All voltages must be
balanced within 8 volts. If unbalanced voltage is measured, refer to Input Voltage Test
(6.3.2).
7. Stop the adjustable frequency drive and remove the input power.
DC capacitors to fully discharge for E-frame size adjustable frequency drives or 20 mi-
nutes for D-frame size adjustable frequency drives.
8. Reconnect the motor leads to the adjustable frequency drive output terminals (U, V, W).
9. Reapply power and restart the adjustable frequency drive. Adjust the motor speed to a
nominal level.
10. Using a clamp-on style ammeter, measure the output current on each output phase. All
currents should be balanced. If unbalanced current is measured, refer to Current Sensor
Test (6.3.14).
®
FC Series
MG.90.L1.22 - VLT ® is a registered Danfoss trademark
6 Test Procedures
Allow 40 minutes for
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