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User Manual
MG430
Digital Insulation Tester/Megohmeter
Introduction
Congratulations on your purchase of Triplett’s Digital Insulation Tester/Megohmmeter. The MG430
provides three test ranges plus continuity and AC/DC voltage measurement. A handy test lock feature
and a data hold function are also included. This professional meter, with proper care, will provide
years of reliable service.
Safety
• Circuits under test must be de-energized and isolated before connections are made (except for
voltage measurements).
• Circuit connections must not be touched during a test. Use extreme caution when working near
bare conductors and bus bars. Accidental contact with conductors could result in electrical
shock.
• Use caution when working near voltages above 60VDC or 30VACrms.
• After insulation tests, capacitors must be discharged.
• Test leads (including alligator clips) must be in good working order, clean and without broken
or cracked insulation.
• When servicing, use only specified replacement parts.
International Safety Symbols
Caution, refer to this manual before using this meter
Dangerous Voltages
Meter is protected throughout by double or reinforced insulation
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Meter Description
1. LCD Display
2. Hold Button
3. Test Button
4. Rotary Switch
5. Lock Button
6. Backlight Button
7. Input Terminals
Operation
Ensure that the circuit under test does not include components that can be damaged by 1000VDC; such
devices include power factor correction capacitors, low voltage mineral insulated cables, electronic light
dimmers, and ballasts/starters for fluorescent lamps.
Connecting Test Leads
For all measurements, connect the red test lead to the V input terminal and the black test lead to
the COM input terminal.
Test Lead Check
Set the rotary switch to the 200range.
Touch the test lead tips together.
Resistance should read less than 0.5 and the audio tone should sound.
With the leads not touching, the display should read infinity indicated by “1”.
Readings displayed other than the readings described above are indicative of a test lead
problem. The test leads must be replaced before using the meter. Failure to do so could
result in damage to equipment and electrical shock.
Insulation Resistance Measurements (Megohmmeter Tests)
Warning: Do not perform Insulation Resistance measurements if AC Voltage is present on the
device under test.
1. Connect the red test lead to the V input terminal; black lead to the COM terminal.
2. Set the function switch to the desired M test voltage position.
3. Connect the tips of the test leads to the equipment under test. If there is a voltage present, a
constant beep will sound and the voltage will be displayed.
4. The display will show “1“until the TEST button is pushed. Press and hold the TEST button.
The upper right display shows the test voltage applied and the flashing high voltage symbol
will be displayed. The main display shows the resistance.
5. Keep the test leads connected to the equipment under test and release the TEST button. The
circuit will discharge through the meter. Keep the test leads connected until the circuit is
completely discharged and the upper right display shows 0 volts.
Warning
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Lock Function
For hands-free operation, use the LOCK feature.
1. With the test leads connected to the equipment under test, simultaneously press the TEST
and LOCK keys.
2. The LOCK icon” ” will appear on the display. A beeper will sound every 2 seconds to
indicate that the meter is in Lock mode.
3. Press the LOCK key to disable the Lock function and end the test.
Notes on IR (Megohmmeter) testing:
5. The maximum measurement range for the 380260 is 2000MΩ. Frequently, insulation
resistance will exceed this value. When this happens, the display will indicate “1”, meaning
AC/DC Voltage Measurement
Resistance Measurement
the resistance is very high and the insulation being tested is good.
6. If the device being tested is highly capacitive, the display will indicate an increasing
resistance value over time. Always wait until the reading has stabilized before recording the
value.
1. Set the Rotary switch to the ACV or DCV position.
2. Connect the red test lead to the V terminal and the black test lead to the COM terminal.
3. Connect the test leads to the circuit under test.
4. Read the voltage value on the LCD.
5.
WARNING
Do not run this test unless ACV = 0. Do not use this mode to check diodes.
1. Set the Rotary switch to the 200k position.
2. Connect the red test lead to the V terminal and the black lead to the COM terminal.
3. Connect the tips of the test leads to the circuit under test.
4. Read the resistance value on the display.
Low Resistance (Continuity) Measurement
1. Set the Rotary switch to the 200Ω position.
2. Connect the red test lead to the V terminal and the black lead to the COM terminal.
3. Connect the tips of the test leads to the circuit under test.
4. Read the resistance value on the display. When the resistance of a circuit is less than approx.
40Ω the audible tone will sound.
Auto Power Off
To conserve battery life, the meter will automatically turn off after approx. 15 minutes of non-use. To
turn the meter back on, turn the rotary switch to OFF, then to the desired function.
Hold Function
The hold function freezes the reading in the display. Press the HOLD key momentarily to activate or
to exit the hold function
Backlight
Press the key for to turn on the display backlight function. The backlight will automatically turn off
after 15 seconds.
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Applications
Motor
Starter
Mains
Line
Switch
GND
Notes:
1. The STARTER must be in the ON position during the
Measuring Power Tools and Small Appliances
This section applies to any device under test that uses a line cord. For
double insulated power tools, the meter’s leads should be connected to
the device’s housing (chuck, blade, etc.) and the lines of the power
cord.
Testing AC Motors
Disconnect the motor from the line by disconnecting the wires from the motor terminals or opening
the mains switch.
If the mains switch is opened, and the motor also has a motor-starter, then the starter must be held
in the ON position. With the mains switch opened, the measured resistance will include the
resistance of the motor wire and all 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 one meter lead to the grounded motor housing and
the other lead to one of the motor leads. Refer to diagram at below.
Testing DC Motors
1. Disconnect the motor from the line.
2. To test the brush rigging, field coils and armature, connect one meter lead to the grounded
motor housing and the other lead to the brush on the commutator.
3. If the resistance measurement indicates a weakness, raise the brushes off of the commutator
and separately test the armature, field coils and brush rigging (one at a time). Leave one lead
connected to the grounded motor housing while testing the motor components. This also
applies to DC Generators.
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Specifications
Range
Resolution
Accurac
y
Terminal Voltage
200M 250V
0.1M
±3% + 5d
250V + 10% ~ -0%
200M 500V
0.1M
±3% + 5d
500V + 10% ~ -0%
0-1000M 1000VDC
1M
±3% + 5d
1000V + 10% ~ -0%
1000-2000M 1000VDC
1M
±5% + 5d
1000V + 10% ~ -0%
Range
Test Current
Short Circuit
Current
200M 250V
250k (load)
200M 500V
1mA
500k (load)
<1mA
0-1000M 1000VDC
1M
1000-2000M 1000VDC
AC VOLTAGE (40Hz400Hz)
Range
Resolution
Accuracy
Input
Impedance
Overload
Protection
750VAC
1V
±1.2% + 10d
10M
750Vrms
Range Specifications
Accuracies are specified as % reading + digits at 23oC ± 5oC < 80% RH
MEGOHMMETER RANGES
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DC VOLTAGE
Range
Resolution
Accuracy
Input
Impedance
Overload
Protection
1000VDC
1V
±0.8% +
3d
10M
1000Vrms
RESISTANCE
Range
Resolution
Accuracy
Max. Open
Circuit
Overload
Voltage
Protection
200
0.1
±1% + 2d
4.5V
250Vrms
200k
0.1k
±1% + 2d
3V
250Vrms
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General specifications
Display LCD with dual display
Sampling rate 2.5 readings per second
Continuity beeper <40 Ω, short circuit current <200mA, open circuit
voltage 4.5V
Over range indicator ‘1’ displayed
Zero adjust Automatic
Low battery indicator Low battery symbol displayed when battery
Environmental Installation category III, Pollution Degree 2,
Altitude up to 2000
Power source Six (6) 1.5 ‘AA’ batteries
Fuse 250mA/600V ceramic 3AG Fast blow
Operating conditions 0 to 40
Storage conditions -10 to 60
Dimensions 200 x 92 x 50mm (7.8 x 3.6 x 1.9”)
Weight 700g (24.6oz)
IEC 1010 CAT III-1000V
Approvals
voltage is low
meters, Indoor use only
o
C (32 to 104oF); 80% RH
o
C (14 to 140oF); <80% RH
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Maintenance
Battery Replacement
When the low battery symbol appears on the
LCD, the six 1.5V ‘AA’ batteries must be
replaced.
1. Turn the meter off and remove the test leads
2. Unsnap the tilt stand from the rear of the meter
3. Remove the four Phillips head screws holding the
battery cover
4. Remove the battery compartment cover
5. Replace the batteries observing polarity
6. Affix the rear cover and secure the screws.
7. Reattach the tilt stand
Warranty Information
Triplett / Jewell Instruments extends the following warranty to the original
purchaser of these goods for use. Triplett warrants to the original purchaser for
use that the products sold by it will be free from defects in workmanship and
material for a period of (1) one year from the date of purchase. This warranty
does not apply to any of our products which have been repaired or altered by
unauthorized persons in any way or purchased from unauthorized distributors so
as, in our sole judgment, to injure their stability or reliability, or which have been
subject to misuse, abuse, misapplication, negligence, accident or which have
had the serial numbers altered, defaced, or removed. Accessories, including
batteries are not covered by this warranty
Copyright © 2019 Triplett
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