AEMC 4500 - Fuse Replacement, Cleaning, and Calibration

38 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qualied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20Ω.
• 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).