Danfoss VLT series, Руководство по обслуживанию

Страница: 81 / 158

5-15
VLT is a registered Danfoss trademark
5.2.2 Switch Mode Power Supply (SMPS) Test
The SMPS derives its power from the DC bus. The first indication
that the DC bus is charged is the DC bus charge indicator
being lit. This LED however can be lit at a voltage still to low to
enable the power supplies.
First test for the presence of the DC bus.
1. Using a voltmeter, read DC bus voltage at
power card connector MK105 (A) with respect
to MK105 (B). Meter should indicate
approximately 1.38 x AC input voltage to drive.
2. If voltage is correct proceed to set 3. If voltage is
present but out of range, proceed to DC Under
Voltage test. If voltage is at zero, proceed to
Zero DC Bus Voltage test.
3. Test remaining power supplies. Insert signal test
board into interface card connector MK104
4 . Connect negative (-) meter lead to terminal 4
(common) of signal board. With positive (+)
meter lead check the following terminals on
signal board.
Terminal Supply Voltage Range
11 +18V 16.5 to 19.5 VDC
12 -18V -16.5 to -19.5 VDC
23 +24V 23 to 25 VDC
24 +5V 4.75 to 5.25 VDC
In addition, the signal test board contains three LED indicators
that indicate the presence of voltage as follows:
Red LED +/- 18VDC supplies present
Yellow LED +24VDC supply present
Green LED +5VDC supply present
The lack of any one of these power supplies indicates the low
voltage supplies on the power card are defective. This assumes
of course that the proper DC bus voltage was read at power
card connector MK105 (A) and (B). Replace the power card in
accordance with the disassembly procedures in Section 6 or 7.
5.2.3 Zero DC Bus Voltage Test
If no voltage is present at power card connector MK105 (A)
and (B), check the condition of the DC power supply fuse. For
D-size frames, the DC power supply fuse is located beneath
the power card. For E-size frames, the fuse is located on the
power card mounting plate next to the power card. It can be
tested without disassembling the unit.
1. Remove power to drive and ensure DC bus is
fully discharged by measuring voltage at power
card connector MK105 (A) with respect to
MK105 (B).
If DC power supply fuse is open (blown), it is
not possible to detect the presence of bus
voltage at these terminals. If uncertain, wait 20
minutes for D-frame sizes or 40 minutes for E-
frames sizes to allow DC bus to fully discharge.
2. With ohmmeter set on diode scale or Rx100,
measure from power card connector MK105 (A)
to any bus bars coming from DC inductor. Bus
bars are visible at lower edge and beneath
power card mounting bracket. Depending on
bus bar read, look for a diode drop or complete
short. In either case this indicates a fuse is in the
circuit providing a path for continuity. An open
reading indicates open fuse.
If the fuse is open, it indicates a failure of the power supplies
on the power card. The power card and fuse require
replacement. If the fuse checks good, there may be a problem
with the soft charge circuitry. Proceed to the static checks of
the soft charge and rectifier circuits earlier in this section.
CAUTION
!