Checking Power Modules And Motor Input With Input; Power Off - Static Test; Servicing The Drive - Carrier 19XRV Start-Up And Service Instructions

Checking Power Modules and Motor Input with
Input Power Off — Static Test
Use the following procedure to check the drive's power module
circuitry with power off:
1. Turn off and lock out input power. Wait appropriate time
as per Danfoss VFD nameplate.
2. Verify there is no voltage at the drive's input power terminals.
3. Using a voltmeter, check the DC bus potential as described
in the section Verifying That DC Bus Capacitors Are Dis-
charged to ensure the DC bus capacitors are discharged.
4. Disconnect the motor from the drive.
5. Check all AC line and DC bus fuses.
6. Use a multimeter to perform a static check on the input
diodes and output IGBTs. See Table 7. For parallel drives
this test will have to be done for each individual drive
module, so in addition to removing the input and motor
busbars for parallel drives the DC link connection will
have to be removed for the individual drives.
7. Check motor impedance.
8. Reconnect the motor to the drive.
9. Reapply input power.
WARNING
DC bus capacitors retain hazardous voltages after input power
has been disconnected. After disconnecting input power, wait
the time specified in Table 1 or as specified on the Danfoss
VFD nameplate. For the DC bus capacitors to discharge and
then check the voltage with a voltmeter rated for the DC bus
voltage to ensure the DC bus capacitors are discharged before
touching any internal components. For parallel drive modules
(N630 and larger) check voltage before and after the individual
DC fuses. Failure to observe this precaution could result in se-
vere bodily injury or loss of life.
An isolated multimeter will be needed to measure DC bus
voltage and to make resistance checks.
Table 7 — Diode Checks
METER LEAD
(+)
R
S
T
U
V
W
DC+
DC-
Digital meters require a special diode check function because the
current sourced by the meter during a normal resistance (Ohms)
METER READING
(-)
DC+ 0.3 to 0.7 v
DC- Infinite (OL)
DC+ 0.3 to 0.7 v
DC- Infinite (OL)
DC+ 0.3 to 0.7 v
DC- Infinite (OL)
DC+ 0.3 to 0.7 v
DC- Infinite (OL)
DC+ 0.3 to 0.7 v
DC- Infinite (OL)
DC+ 0.3 to 0.7 v
DC- Infinite (OL)
R
S
T
Infinite (OL)
U
V
W
R
S
T
0.5 v
U
V
W
test is too low to accurately test a diode. Make sure the meter is set
to the diode test function. Voltage readings may not be exact as
shown in above table, but look for consistency during each of the
4 tests. When performing a test that should return infinity (OL) as
shown in above table, you should see a value slowly climbing to-
ward infinity. This is a result of the meter charging a capacitor and
is normal.
If an incorrect reading is observed associated with U, V, W (out-
puts) this indicates a failed inverter IGBT module. Replace the
shorted IGBT modules. Similarly if an incorrect reading is ob-
served associated with R, S, T (inputs) this indicates a shorted
SCR. Replace the shorted SCR module.

Servicing the Drive

To guard against possible personal injury and/or equipment
damage:
1. Inspect all lifting hardware for proper attachment
before lifting drive.
2. Do not allow any part of the drive or lifting mechanism
to make contact with electrically charged conductors or
components.
3. Do not subject the drive to high rates of acceleration or
deceleration while transporting to the mounting loca-
tion or when lifting.
Do not allow personnel or their limbs directly underneath the
drive when it is being lifted and mounted.
DC bus capacitors retain hazardous voltages after input power
has been disconnected. After disconnecting input power, wait
the time specified in Table 1 or as specified on the Danfoss
VFD nameplate. For the DC bus capacitors to discharge and
then check the voltage with a voltmeter rated for the DC bus
voltage to ensure the DC bus capacitors are discharged before
touching any internal components. For parallel drive modules
(N630 and larger) check voltage before and after the individual
DC fuses. Failure to observe this precaution could result in se-
vere bodily injury or loss of life.
An isolated multimeter will be needed to measure DC bus
voltage and to make resistance checks.
Refer to Fig. 33 for location of DC bus terminals.
1
L1 L2 L3
2
DC BUS TEST DC+ DC–
TERMINALS
LOCATED INSIDE
ACCESS DOOR
Fig. 33 — Check DC Bus Terminals
For FC-102 service guide lines, refer to Danfoss Manuals; the lat-
est Service Guide for VLT FC Series is MG94A502.
30
WARNING
WARNING
I
LOCKOUT/TAGOUT
O
A19-1814
0V
0V
MULTIMETER