Extech Instruments MG500 User manual

USER MANUAL
10KV Digital High Voltage Insulation Tester
Model MG500
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Introduction
Thank you for selecting the Extech Instruments Model MG500. This device is shipped fully tested
and calibrated and, with proper use, will provide years of reliable service. Please visit our website
(www.extech.com) to check for the latest version of this User Guide, Product Updates, and
Customer Support.
Safety
International Safety Symbols
This symbol, adjacent to another symbol or terminal, indicates the user must refer to the manual for
further information.
This symbol, adjacent to a terminal, indicates that, under normal use, hazardous voltages may be
present
Double insulation
CAUTION RISK OF ELECTRIC SHOCK
This tester has been designed with safety in mind. However, no design can completely protect
against incorrect use. Electrical circuits can be dangerous and lethal when a lack of caution and
poor safety practices are used.
Do not take field measurements on either power system grounding during periods of lightning
activity, or any non-insulated system or non-insulated circuit. In the event that lightning occurs,
stop all testing and isolate and remove any temporarily installed test spikes or test leads.
Preparations for testing power system grounding (or close to it) can leave personnel vulnerable to
exposure caused by faults at, or fed from, the system under test, transferred potentials from
remote test grounds, and inadvertent line energizing. Always insulate the device under test.
While the probability of such occurrences is low, personnel safety will, nevertheless, be
enhanced by the following:
When working near high tension systems rubber gloves and shoes should be worn. Work on
clean, dry crushed rock or an insulating blanket. Avoid bare hand-to-hand contact between
the tester and extended test leads.
When using the tester with test leads, ensure that they are safe and properly authorized.
Disconnect the tester from any external circuit when checking or changing the fuse and/or
batteries.
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CAUTION! READ THE MANUAL
Follow the instructions in the Manual for every measurement type. Read and understand the
general instructions before attempting to use this instrument.
SAFETY CHECK
Before using the tester check the condition of the test leads.
The test leads must be free of cracks or any damages and must be insulated.
Always disconnect the test leads when changing the batteries
Always double check the lead connections before making any measurements. For increased
safety, use fused test leads (optional).
Do not touch exposed wiring, connections or other "live" parts of an electrical circuit. If in doubt,
check the circuit first for voltage before touching it.
THIS INSTRUMENT SHOULD ONLY BE USED BY COMPETENT, SUITABLY TRAINED
PERSONNEL.
CAUTION! RISK OF ELECTRIC SHOCK
CAUTION! READ THE MANUAL
Electricity can cause severe injuries even with low voltage or current. It is extremely important that
the following information be read before using this High Voltage Digital Insulation Meter.
This instrument must only be used and operated by competent trained personnel and in strict
accordance with the instructions and safety practices. Liability is not accepted for any damage or
injury caused by misuse or non-compliance with instructions and safety procedures.
This instrument must not be used on live circuits. Ensure all circuits are de-energized before
testing.
Never open this High Voltage Digital Insulation Meter except for battery replacement (See
Battery Replacement section).
Always inspect this High Voltage Digital Insulation Meter and test leads before using for any
sign of abnormality or damage. If any abnormal conditions exist (broken test leads, cracked
case, display faulty etc...) do not attempt to take any measurement or use the tester. Return
the Meter for service.
This Variable High Voltage Digital Insulation Meter has a live circuit warning beeper. If it is
connected to a live circuit, a rapid pulsating tone will sound and a warning message will be
displayed. In this case, stop testing and immediately disconnect the instrument from the
circuit under test.
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Features
•Insulation Resistance Testing
This digital insulation resistance tester will measure insulation resistance from 800k ohms to
500G ohms using Dynamic Auto-ranging technology. Test voltages range from 500V to 10kV
in 500 Volt steps. This instrument also employs an Auto-Discharge utility.
•DAR: Dielectric Absorption Ratio Testing
The Dielectric Absorption is the ratio of the Insulation Resistance, measured at 60 seconds,
divided by the Insulation Resistance measured at 30 seconds).
DAR = Resistance measured at 1 minute / Resistance measured at 30 seconds
•PI: Polarization Index Testing
The Polarization Index is the ratio of the Insulation Resistance measured at 10 minutes
divided by the Insulation Resistance measured at 1 minute.
PI = Resistance measured at 10 minutes / Resistance measured at 1 minute
•Automatic Discharge of Capacitive and Inductive Circuits
This instrument will automatically discharge all circuits, charged by the tester, upon
completion of a test. The discharge can be observed on the instrument’s bargraph display.
•Automatic Battery Test
When the instrument is first powered ON, a test circuit applies a heavy current draw on the
batteries for a few seconds and measures the voltage in order to determine the capacity of
the batteries. The result is shown on the display.
•Normal Operation Mode Considerations
This instrument uses Dynamic Current Auto-ranging technology. The bar graph will
display the voltage that is stressing the insulation during the first 30 seconds of a test and
during the discharge of the circuits at the end of the test. The display will also show the
elapsed time from the start of the test and the total time, even after the testing has stopped.
•Supplemental Features
oInsulation Resistance auto-ranging on all Voltage ranges
oAutomatic DAR calculation
oAutomatic PI calculation
oEner-Save™ Mode conserves battery energy during Insulation Resistance testing
oOverload protection
oLow battery indicator
oAuto Off feature
oWarning of external voltage presence (>500VAC or VDC)
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Description
1. Negative High Voltage (HV) Terminal
(Earth Ground)
2. Dot Matrix Display window
3. GUARD connection Terminal
4. Positive High Voltage Line Terminal
5. 10KV test voltage preset button
6. Power OFF button
7. Voltage adjustment button (-)
8. 5KV test voltage preset button
9. TEST START/STOP button
10. 2.5KV test voltage preset button
11. 500V test voltage adjust button (+)
12. Power ON button
13. 1KV test voltage preset button
Note: Battery compartment located on bottom of instrument and test lead compartment
located behind the upper faceplate.
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Meter Preparation
Warning: Ensure that the circuit under test does not include devices or components that can be
damaged by 10KVDC; such devices include power factor correction capacitors, low voltage mineral
insulated cables, electronic light dimmers, ballasts and starters for fluorescent lamps.
Connecting the Test Leads to the meter
oConnect the Red (Line) test lead to the Red test jack on the meter.
oConnect the blue lead (attached to the Red test lead) to the Blue test jack on the meter.
oConnect the Green (Earth) test lead to the Green test jack on the meter.
Optional Leakage guard
Connect the optional Blue (Leakage guard), test lead to the Blue test jack.
NOTE: The Blue (Leakage guard)lead is attached directly to the top of the Blue guard lead of the
Red test lead.
Connecting the Test Leads to the device under test
Warning: make sure that the circuit under test is de-energized.
oConnect the Green (Earth) lead to the Earth or ground side of the insulator under Test.
oConnect the Red (Line) test lead to the other side of the Insulator under test.
oOptional Leakage guard: Connect the Blue (Guard) lead to the insulator sheathing and
covering material as shown on the diagram. Use a copper wire wrapped around the
insulator at about its center.
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Operation
Powering the meter
Press the ON button to turn the unit on. Press the OFF button to turn the unit off. If the meter
does not switch ON please check that fresh ‘C’ 1.5V alkaline batteries are installed in the battery
compartment located at the bottom of the instrument.
Insulation Resistance Testing Procedure
Warning: The circuit under test must be completely de-energized and isolated before making
test connections.
1. After turning the unit on, make sure that the Replace Battery message is not displayed. If
the Replace Battery message is displayed replace the batteries before proceeding.
2. The test voltage defaults to 2500V on power up. Select the desired test voltage using the
Voltage Adjust buttons (±500V) that step through the available test voltages in 500V
increments or by pressing one of the preset test voltage buttons (10kV, 5kV, 2.5kV, 1Kv).
3. The display shows the Connect Leads prompt along with the selected test voltage value.
Connect the Green test lead to the Green test socket on the meter and then to the Ground
side of the insulator under test.
Connect the Red lead to the Red test socket on the meter and the Blue guard cable to the
blue socket on the meter. Connect the service end of the Red cable to other side of the
insulator under test.
If a Leakage Guard lead is required to collect surface leakage, connect the separate Blue test
lead into the Blue guard lead from the Red test lead which is plugged into the Blue test
socket on the meter and then clip the service end of the cable to the surface of the insulator
under test.
4. Momentarily Press the TEST START/STOP button (1.5s 〜3 seconds) to start testing.
For DAR or PI testing – refer to the separate test procedure below.
5. The Insulation resistance test will complete in 5 seconds. The test voltage percentage
steadily counts down to zero during the test as can be seen on the display. The resistance
test result value will appear on the display when the test has completed.
6. The HOLD icon will appear in place of the bargraph when the test is complete and after the
voltage has been discharged.
WARNING: DO NOT REMOVE THE TEST LEADS BEFORE THE HOLD DISPLAY APPEARS.
7. The meter automatically discharges the system at the end of the test.
8. To take another test, press the TEST START/STOP button, the Connect Leads prompt should
appear on the display; the instrument is now ready to run a new test.
9. The instrument automatically powers down after 5 minutes of inactivity.
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The EnersaveTM Mode
EnersaveTM mode conserves battery life by performing a relatively short test. The EnersaveTM
mode is the default test mode. To bypass this mode and run a longer test (10 minutes) press and
hold the TEST button for more than 3 seconds when starting a test.
DAR and PI Tests (DAR: Dielectric Absorption Ratio) and (PI: Polarization Index)
Warning: The circuit under test must be completely de-energized and isolated before making
test connections.
1. After turning the unit on, make sure that the Replace Battery message is not displayed. If
the Replace Battery message is displayed replace the batteries before proceeding.
2. The test voltage defaults to 2500V on power up. Select the desired test voltage using the
Voltage Adjust buttons (±500V) that step through the available test voltages in 500V
increments or by pressing one of the preset test voltage buttons (10kV, 5kV, 2.5kV, 1Kv).
3. The display shows the Connect Leads prompt along with the selected test voltage value.
Connect the Green test lead to the Green test socket on the meter and then to the Ground
side of the insulator under test.
Connect the Red lead to the Red test socket on the meter and the Blue guard cable to the
blue socket on the meter. Connect the service end of the Red cable to other side of the
insulator under test.
If a Leakage Guard lead is required to collect surface leakage, connect the separate Blue test
lead into the Blue guard lead from the Red test lead which is plugged into the Blue test
socket on the meter and then clip the service end of the cable to the surface of the
insulator under test.
4. Press and hold the Test Start/Stop button for more than 3 seconds to the initiate DAR/PI
testing mode.
5. After 1 minute, the elapsed test timer appears on the upper line (right hand side) of the
display. The resistance reading is shown on the upper left hand side of the display. The lower
line shows the test voltage and the DAR value.
6. After 10 minutes, the test completes. The display will show the results:
R= (resistance or OVER R for over range)
T= Hold, T = 10:00, V = (test voltage)
PI = (PI value)
DAR = (DAR value)
7. To take another test, press the TEST START/STOP button, the Connect Leads prompt should
appear on the display; the instrument is now ready to run a new test.
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Bargraph Voltage Display
The bargraph represents the voltage present on the test leads as it rises, soaks, and decays. The
bargraph appears on the lower left of the display window during a test.
Automatic Under/Over Range Resistance Detect
If the display shows the message “LOW M-ohms”, the test should be interrupted immediately by
pressing the TEST button. This message indicates that the insulation under test has broken down
and the meter is trying to inject a high potential onto a short circuit. If ‘HIGH’ appears, it is likely
that the test configuration is open. Check the test set-up and then test again.
Elapsed Timer
The test duration is indicated on the display. This is particularly useful in determining whether an
insulating material under test will break down in a given amount of time.
Manual Test STOP
To stop a test in progress, press the TEST button. The test will immediately end and the system
will automatically discharge.
Automatic Test STOP
When in the default EnersaveTM mode, the test automatically stops in 5 seconds. When not in
the EnersaveTM mode the test automatically stops after approx. 10 minutes.
Live Circuit Warning
If the test leads are connected to a live circuit (approx. 500V), a warning beeper will sound and
the meter will display “Live Warning…Circuit Live…” In this case, correct the problem and retest.
Automatic Discharge
At the end of a test, the meter automatically discharges the high voltage. The automatic
discharge status is reflected on the display. During discharge the beeper will sound and, when
completely discharged, the HOLD icon will appear on the display.
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Application-Specific Information
Measuring Power Tools and Small Appliances
For small appliances, connect the GREEN (EARTH) lead to conductors and the RED (LINE) lead to
insulating material.
For single or double insulated power tools, one lead should be connected to the device’s chuck,
blade, etc. and the other lead to one of the AC power cord conductors (test both conductors in
turn). Refer to the power tool application diagram below.
AC Motor Test
Disconnect the motor from the line by:
a. Disconnecting the wires from the motor
terminals or,
b. Opening the main switch
If the main switch is opened, and the motor has a motor-starter, then the starter must be held in
the ON position. With the main switch opened, the measured resistance will include the
resistance of the motor wire and all of the other components between the motor and the main
switch. If a weakness is indicated, the motor and other components should be checked
individually. If the motor is disconnected at the motor terminals, connect the RED lead to the
grounded motor housing and the GREEN lead to one of the motor leads.
AC
Plug
For 2 or 3 prong plugs, connect the
RED lead to one conductor at a time
Connect the GREEN
lead to the chuck
Connect RED lead
to grounded housing
Connect GREEN lead
to the motor leads
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