IMPULSE®•G+ & VG+ Series 4 Instruction Manual – February 2017
6-30
Power Section Check
Power Off Checks
To perform a power section check, remove the drive’s main and control wiring from the terminal
strips. Obtain reading as specified in the table on the next, and ensure that the reading falls within
the normal reading range.
Test equipment - Analog Ohmmeter set R x 1 scale or digital multimeter set to the diode.
WARNING
Do NOT touch any circuit components while AC main power is on or immediately after the
main AC power is disconnected from the unit. You must wait until the red “CHARGE” lamp is
extinguished. It may take as long as 10 minutes for the charge on the main DC bus capacitors
to drop to a safe level. Failure to adhere to this warning could result in serious injury.
Device
VOM (on RX1 Scale)
Normal Reading
(Analog Meter)
Normal Reading
(Digital Meter)Positive Lead Negative Lead
Input Rectifier
Bridge *1
L1 +
7–100 Approximately 0.5 V
L2 +
L3 +
–L1
–L2
–L3
L1 –
Infinite OL Displayed
L2 –
L3 –
+L1
+L2
+L3
Bus Capacitors + –
Observe gradually
increasing resistance
Observe gradually
increasing voltage to OL
Pre-charge
Resistor
– Across the Resistors 100 or less –
Output
Transistors
*2
*3
T1 +
7-100 Approximately 0.5V
T2 +
T3 +
–T1
–T2
–T3
T1 –
Infinite OL Displayed
T2 –
T3 –
+T1
+T2
+T3
Braking Diode
B2 B1 10 0.5 V
B1 B2 Infinite OL Displayed
B2 – Infinite OL Displayed
– B2 Infinite 0.5 V
1. “+” could be any one of three (+) terminals which are labeled as
1,
2, and
3.
2. If the bus fuse is blown you must install a jumper across the fuse terminals to get accurate resistance measurements.
3. If the pre-charge resistor is open, you will read infinite W between + and any output terminal unless you install a temporary jumper across the
resistor.
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