Incorrect reading
An incorrect reading can indicate a problem in the inrush
circuit, or with the rectifier. See
DC bus voltage test part II
1.
Power down the drive.
2.
Wait for the DC bus to discharge. See the label
on the drive or control shelf for discharge times.
3.
Remove the control card mounting plate. See
chapter 10.2.2 Control Card and Control Card
Mounting Plate
, or
chapter 13.2.2 Control Card and Control
.
4.
Use an ohmmeter set to measure ohms.
5.
Measure between MK902 pin 1 to DC(+).
6.
Measure between MK902 pin 2 to DC(-).
A short circuit (0
Ω
) is the correct reading for both
measurements.
Incorrect reading
An incorrect reading indicates that the wire harness is
defective. Replace the wire harness.
DC bus voltage test part III
•
In parallel drive systems, remove the common
connecting DC terminal to test individual
modules (by removing the connecting busbars or
DC fuses).
•
Measure across fuse F901 on the top of the
power card.
An open fuse indicates a failure of a supply on the power
card. Replace the power card.
8.5.5 Switch Mode Power Supply Test
The switch mode power supply (SMPS) derives its power
from the DC bus. The first indication that the DC bus is
charged is the DC bus charge indicator light on the power
card being lit. This LED, however, can be lit at a voltage
still too low to enable the power supplies.
First test for the presence of the DC bus.
1.
Install the signal test board.
2.
Install the split bus power supply. Power the
power card using split bus mode. See
.
3.
Connect the negative (-) meter lead to terminal 4
(common) of the signal board. With a positive (+)
meter lead, check the following terminals on the
signal board.
Terminal
Supply
Voltage range
11
(+)18 V
16.5–19.5 V DC
12
(-)18 V
(-)16.5–19.5 V DC
23
(+) 24 V
23–25 V DC
24
(+) 5 V
4.75–5.25 V DC
Table 8.5 Measured Voltages at Select Terminals
In addition, the signal test board contains 3 LED indicators
that show the presence of voltage as follows:
•
Red LED (
±
) 18 V DC supplies present
•
Yellow LED (+) 24 V DC supply present
•
Green LED (+) 5 V DC supply present
The lack of any of these power supplies indicates that the
low voltage supplies on the power card are defective.
Replace the power card as described in
,
, or
.
8.5.6 Input Imbalance of Supply Voltage
Test
Ideally, all 3 phases have an equal current draw. Some
imbalance is possible, however, due to variations in the
phase-to-phase input voltage.
A current measurement of each phase reveals the balanced
condition of the line. To obtain an accurate reading, it is
necessary for the drive to run at more than 40% of its
rated load.
1.
Perform the input voltage test before checking
the current as described in
. Voltage imbalances automatically
result in a corresponding current imbalance.
2.
Apply power to the drive and place it in run
mode.
3.
Using a clamp-on amp meter (analog preferred),
read the current on each of 3 input lines at L1(R),
L2(S), and L3(T). Typically, the current does not
vary from phase to phase by more than 5%. If a
greater current variation exists, it indicates a
possible problem with the mains supply, or a
problem within the drive itself.
One way to determine if the mains supply is at
fault is to swap 2 of the incoming phases. If all 3
phases are different, swap the phase with the
highest current with the phase with the lowest
current.
4.
Remove power to drive.
5.
Swap the phase.
6.
Reapply power to the drive and place it in run.
7.
Repeat the current measurements.
Test Procedures
VLT
®
FC Series, D1h–D8h, Da2/Db2/Da4/Db4, E1h–E4h, J8/J9
108
Danfoss A/S © 02/2019 All rights reserved.
MG94A502
8
8
Содержание VLT FC Series
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