Main rectifier circuit test E-frames part I
1.
Connect the positive (+) meter lead to the positive (+) DC bus connector MK105 (A) on
the power card.
2.
Connect the negative (–) meter lead to terminals L1, L2, and L3 in sequence. If a dis-
connect option is used, measure on top side of fuses.
Each reading should show infinity. The meter will start at a low value and slowly climb towards
infinity due to capacitance within the adjustable frequency drive being charged by the meter.
Incorrect reading
With the Part I test connection, the SCR modules are blocking current flow. A short indicates a
shorted SCR module.
Main rectifier circuit test E-frames part II
1.
Reverse meter leads by connecting the negative (–) meter lead to the positive (+) DC
bus connector MK105 (A) on the power card.
2.
Connect the positive (+) meter lead to L1, L2, and L3 in sequence. Each reading should
show open.
Incorrect reading
With the Part II test connection, the SCR modules are blocking current flow. A short indicates a
shorted SCR module.
Main rectifier circuit test E-frames part III
1.
Connect the positive (+) meter lead to the negative (-) DC bus connector MK105 (B) on
the power card.
2.
Connect the negative (–) meter lead to terminals L1, L2 and L3 in sequence. Each reading
should show a diode drop.
Incorrect reading
With the Part III test connection, the diodes in the main rectifier diode modules are forward biased.
The meter reads the diode drops. If a short circuit or an open circuit exists, the diode module is
damaged.
Main rectifier circuit test E-frames part IV
1.
Reverse meter leads by connecting the negative (–) meter lead to the negative (-) DC
bus connector MK105 (B) on the power card.
2.
Connect the positive (+) meter lead to L1, L2 and L3 in sequence. Each reading should
show infinity.
Each reading should show infinity. The meter will start at a low value and slowly climb toward
infinity due to capacitance within the adjustable frequency drive being charged by the meter.
Incorrect reading
With the Part IV test connection, the diodes in the main diode modules are reversed biased. If a
short circuit exists, the diode module is damaged.
Continue to Soft Charge Rectifier Tests: E-frames.
6 Test Procedures
High Power Service Manual for VLT
®
FC Series
Adjustable Frequency Drives
6-10
MG.90.L1.22 - VLT
®
is a registered Danfoss trademark
6
Summary of Contents for VLT HVAC FC 100
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