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Digital Ground Resistance Tester Model 4500
CHAPTER 5
MAINTENANCE
5.1 Warning
Please make sure that you have already read and fully understand the
WARNING section on page 3.
• To avoid electrical shock, do not attempt to perform any servicing
unless you are qualified to do so.
• To avoid electrical shock and/or damage to the instrument, do not get
water or other foreign agents into the case. Turn the Instrument OFF
and disconnect the unit from all circuits before opening the case.
5.2
Power Supply
5.2.1 Testing Battery Voltage
• Short-circuit the X and Z terminals.
• Turn the current selector (see Figure 3) to 50 mA.
• Turn the range selector to 20
Ω
.
• Press the “Test” button.
If the colon (“8” in Figure 3) lights up, recharge the batteries. If the colon
does not light, the batteries are charged.
5.2.2 Average Operating Time
• 4hrs on 50mA test current (800 15-second measurements)
• 7hrs on 2mA and 10mA test currents (1500 15-second measure
-
ments)
If the colon lights up, the battery has lost power. Thereafter, the
available operating time remaining is approximately 100 15-second
measurements.
When this situation arises, recharge the battery at once or obtain power
from an external battery (see the following paragraphs).
