Komatsu 960E-1 -, Shop Manual, Page: 47 / 51

00 Index and foreword CEN00002-05
29
Manual discharge of capacitors
If the voltage is greater than 1V on any of the capaci-
tors, the capacitor must be manually discharged.
With a suitable capacitor discharge device, such as
ground stick pair (PC3299), discharge the capacitors
where needed per the following instructions:
1. With the control cabinet high voltage compart-
ment doors closed, connect the ground stick
pair ground lead to ground. The most conve-
nient location is the middle top bolt that attaches
the door center post to the control cabinet
frame.
2. Verify the ground connection and ground stick
resistance levels. Measure the resistance
between each individual ground stick tip to
either the GND1 or GND2 ground block in the
low voltage compartment of the control cabinet
using a multimeter (Figure 00-9). Ensure that
the resistance is within the manufacturer’s spec-
ifications for the ground sticks.
For PC3299 grounding sticks, the valid range is
80 to 125 ohms per stick.
Hazardous voltages are present in this equip-
ment. Avoid touching any energized equipment
when the door to the low voltage area is open.
Failure to do so may result in personal injury and
equipment damage.
3. Discharge the relevant capacitors. Open the
door(s) and place one grounding stick on one of
the positive (+) capacitor terminals and the other
on the diagonally located negative (-) terminal.
Refer to Figure 00-8 and Figure 00-10. Attempt
to minimize the time between application of the
positive stick and the negative stick so that the
current flow will be positive to negative rather
than either to ground. Leave sticks in place until
capacitors are discharged. Refer to Figure 00-
10.
NOTE: On the capacitors located behind the door
post, it is difficult to access diagonal terminals on the
same capacitor. If using adjacent terminals, use care
to keep the tips separated while discharging or else
use a positive terminal on one capacitor and negative
terminal of the adjacent capacitor on the same bus
bar.
For PC3299 grounding sticks, the discharge times
from 2000 volts are:
• 15 seconds (maximum) for 2 capacitors
• 75 seconds (maximum) for 10 capacitors
FIGURE 00-9. GROUNDING STICK LEAD CONNECTION AND CHECK