bonitron M3460UC, Customer Reference Manual

Page: 31 / 56

User’s Manual
31
4.8.1. D
ETERMINING THE
DC B
US
T
HRESHOLD
V
OLTAGE
S
ETTING
U
SING THE
T
EST
M
ODE
The DC bus threshold voltage setting may be checked with the drive connected
using the test input to put the M3460 in Test mode. This raises the DC bus
voltage approximately 50-100V above the actual DC bus threshold voltage
setting, and is a fair indication of how the system is set. This has the advantage
of not having to remove the AC power, and can actually be done while the
system is loaded.
Please note:
•
If heavily loaded, the M3460 may run in current limit and the DC bus voltage
may not rise as much as if it were unloaded.
•
If the DC bus threshold voltage is set too high, the DC bus test voltage may
be limited by the overvoltage setting of the M3460, thus providing an
inaccurate result.
The M3460 may shutdown from the timeout feature, depending on the load.
1. Monitor the output DC bus of the M3460, or the input DC bus to the
drive, if connected.
2. Initiate a test with the display.
3. Monitor the DC bus voltage while the M3460 is in Test mode. This is
the DC bus test voltage setting.
The DC bus test voltage setting is approximately 50-100V higher than the DC
bus threshold voltage setting.
For example, for an M3460 with an input voltage of 460VAC, the DC bus
threshold voltage setting is preset to be 585VDC and the DC bus test voltage
setting is preset for an increase of 100VDC. Initiating the test described above
would cause the DC bus voltage to rise to 685VDC (585VDC + 100VDC).
Subtracting the DC bus test voltage (100VDC) from this reading shows that the
actual DC bus threshold voltage setting is 585VDC.
4.8.2. A
DJUSTING THE
DC B
US
T
HRESHOLD
V
OLTAGE
S
ETTING
Adjustment of R7 on the 3460C1 control board (see Figure 4-2) is used to
adjust the DC bus threshold voltage setting. Adjusting the pot in a clockwise
direction will raise the setting. Alternately, a counter-clockwise adjustment of
the pot will lower the setting.
After making the adjustments, repeat the test to verify the new setpoint. Fine
tune the adjustment and retest as necessary.