Danfoss VLT 3032 Service Manual page 23

TESTING THE
SOFT CHARGE CIRCUIT
(SHOWN WITH CONTROL/INTERFACE
CARD CARRIER REMOVED)
1. Prior to making the test, it is necessary to verify that the three soft
charge fuses (F4, F5, and F6) are good. If they are not, they must be
replaced before proceeding.
2. Remove the plug on spade connectors from the plus and minus
terminals of the rectifier bridge (BR1).
3. Connect the positive (+) meter lead to the positive terminal of the
rectifier. Connect the negative (–) meter lead to the soft charge fuses
(F4, F5, and F6) in turn. Each reading should show open.
4. Reverse the meter leads connecting the
(–) lead to the positive terminal of the rectifier
and the (+) lead to the soft charge fuses (F4,
F5, and F6) in turn. Each reading should show
a diode drop.
5. Connect the positive (+) meter lead to the
negative terminal of the rectifier. Connect the
negative (–) meter lead to the soft charge fuses
(F4, F5, F6) in turn. Each reading should show
a diode drop.
6. Reverse the meter leads connecting the
(–) lead to the negative terminal
rectifier and the (+) lead to the soft charge
fuses (F4, F5, and F6) in turn. Each reading
should show open.
7. Set the meter on the lowest resistance
scale. Connect the positive (+) meter lead to
the wire previously removed from the positive
terminal of the rectifier. Connect the negative
(–) meter lead to the positive bus rail on the
input rectifiers. The positive bus rail is the lower
bus bar. The series soft charge resistors (R2
and R3) should read twenty (20) ohms plus or
minus two (2) ohms.
8. Reconnect the wires to the plus and minus
terminals of the bridge rectifier (BR1). Test is
complete.
NOTE: Finding a shorted Soft Charge Rectifier and/or open Soft Charge
Resistor may indicate a short circuit on the DC bus. Continue with the
remaining static test procedures prior to applying power.
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