Soft Charge And Rectifier Circuits Test: E-Frame Sizes; Soft Charge Card Fuse Location - Danfoss VLT Series Service Manual

5.1.3 Soft Charge and Rectifier Circuits Test:
E-frame Sizes
For E-frame size drives, the rectifier and soft charge circuits
are tested separately. The soft charge circuit is made up of
the soft charge rectifier, fuses and the soft charge resistor.
The rectifier circuit is made up of the SCR and diode modules.
The soft charge resistor limits the inrush current when power
is applied to the drive. The soft charge circuit card also provides
snubbing for the SCRs.
It is important to pay close attention to the polarity of the meter
leads to ensure identification of a faulty component should an
incorrect reading appear.
Prior to making the test, it is necessary to ensure the soft
charge fuses, F1, F2, and F3, located on the soft charge card,
are good. An open fuse could indicate a problem in the soft
charge curcuit. Continue test procedures.
Figure 5-4 shows the soft charge card and the location of the
fuses. It is for reference only. It is not necessary to remove the
card to perform the tests.
Disconnect MK3 from the soft charge card and leave
disconected until completion of soft charge and rectifier tests.
5.1.3.1 Soft Charge Fuse Test
Use a digital ohmmeter to test continuity on rectifier fuses F1,
F2, and F3 on the soft chanrge card.
1. Measure F1 across fuse. Open reading indicates
open (blown) fuse.
2. Measure F2 across fuse. Open reading indicates
open (blown) fuse.
3. Measure F3 across fuse. Open reading indicates
open (blown) fuse.
A measurement of 0 ohms indicates good continuity. Replace
any open fuse (infinite resistance).
5-6
VLT is a registered Danfoss trademark
MK3
(disconnect for soft charge
and rectifier tests)
Fuses F1, F2, F3
Figure 5-4. Soft Charge Card Fuse Location