EXTECH Insulation Tester / Megohmmeter User Guide

: June 7, 2024
: EXTECH

Table of Contents

Introduction
Safety
- International Safety Symbols
Meter Description
Operation
Applications
Maintenance
General specifications
Specifications
Two-year Warranty
Calibration and Repair Services
Contact Customer Support
Documents / Resources

EXTECH Insulation Tester / Megohmmeter

Introduction

Congratulations on your purchase of Extech’s Insulation Tester/Megohmmeter. The Model 380260 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

Meter Description

LCD Display
Hold Button
Test Button
Rotary Switch
Backlight Button
Lock Button
Input Terminals

Operation

Warning
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 Ω input terminal and the black test lead to the COM input terminal.

Test Lead Check

Set the rotary switch to the 200 Ω range.
Touch the test lead tips together.
Resistance should read less than 0.5 Ω 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.

Connect the red test lead to the V Ω input terminal; black lead to the COM terminal.
Set the function switch to the desired M Ω test voltage position.
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.
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.
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.

Lock Function

For hands-free operation, use the LOCK feature.

With the test leads connected to the equipment under test, simultaneously press the TEST and LOCK keys.
The LOCK icon” LOCK” will appear on the display. A beeper will sound every 2 seconds to indicate that the meter is in Lock mode.
Press the LOCK key to disable the Lock function and end the test.

Notes on IR (Megohmmeter) testing:

The maximum measurement range for the 380260 is 2000M Ω. Frequently, insulation resistance will exceed this value. When this happens, the display will indicate “1”, meaning the resistance is very high and the insulation being tested is good.
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.

AC/DC Voltage Measurement

Set the Rotary switch to the ACV or DCV position.
Connect the red test lead to the V Ω terminal and the black test lead to the COM terminal.
Connect the test leads to the circuit under test.
Read the voltage value on the LCD.

Resistance Measurement

WARNING
Do not run this test unless ACV = 0. Do not use this mode to check diodes.

Set the Rotary switch to the 200k Ω position.
Connect the red test lead to the V Ω terminal and the black lead to the COM terminal.
Connect the tips of the test leads to the circuit under test.
Read the resistance value on the display.

Low Resistance (Continuity) Measurement

Set the Rotary switch to the 200 Ω position.
Connect the red test lead to the V Ω terminal and the black lead to the COM terminal.
Connect the tips of the test leads to the circuit under test.
Read the resistance value on the display. When the resistance of a circuit is less than approx. 40 Ω 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.

Applications

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

Disconnect the motor from the line.
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.
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.

Testing Cables

Disconnect the cable under test from the line.
Disconnect the opposite end of the cable to avoid errors as a result of leakage from other equipment.
Check each conductor to ground and/or lead sheath by connecting one meter lead to ground and/or lead sheath and the other meter lead to each of the conductors in turn.
Check insulation resistance between conductors by connecting meter leads to conductors in pairs. Refer to diagram at right.

Maintenance

Battery Replacement

When the low battery symbol appears on the LCD, the six 1.5V ‘AA’ batteries must be replaced.

Turn the meter off and remove the test leads
Unsnap the tilt stand from the rear of the meter
Remove the four Phillips head screws holding the battery cover
Remove the battery compartment cover
Replace the batteries observing polarity
Affix the rear cover and secure the screws.
Reattach the tilt stand

You, as the end user, are legally bound ( EU Battery ordinance ) to return all used batteries, disposal in the household garbage is prohibited! You can hand over your used batteries / accumulators at collection points in your community or wherever batteries / accumulators are sold!

Disposal: Follow the valid legal stipulations in respect of the disposal of the device at the end of its lifecycle

Cleaning

Periodically wipe the case with a dry cloth. Do not use solvents or abrasives to clean this instrument.

General specifications

Display	LCD with dual display
Sampling rate	2.5 readings per second
Continuity beeper	<40Ω, short circuit current <200A, Open circuit voltage

4.5V
Over range indicator| ‘1’ displayed
Zero adjust| Automatic
Low battery indicator| Low battery symbol displayed when battery voltage is low
Environmental| Installation category II, Pollution Degree 2, Altitude up to 2000 meters, Indoor use only
Power source| Six (6) 1.5 ‘AA’ batteries
Fuse| 250mA/600V ceramic 3AG Fast blow
Operating conditions| 32 to 104oF (0 to 40°C); 80% RH
Storage conditions| 14 to 140oF (-10 to 460oC);
Dimensions| 7.8 x 3.6 x 1.9” (200 x 92 x 50mm)
Weight| 24.6oz (700g)
IEC 1010| CAT III-1000V
Approvals|

Specifications

Range Specifications

Accuracies are specified as % reading + digits at 23oC ± 5oC < 80% RH

MEGOHMMETER RANGES

Range

| Resolution| Accuracy|

Terminal Voltage

---|---|---|---

200MW/250VDC

| 0.1M Ω| ±3% + 5d|

250V + 20% ~ -0%

200MW/500VDC

| 0.1M Ω| ±3% + 5d|

500V + 20% ~ -0%

0-1000MW/1000VDC

| 1M Ω| ±3% + 5d|

1000V + 20% ~ -0%

1000-2000MW/1000VDC

| 1M Ω| ±5% + 5d|

1000V + 20% ~ -0%

Range

|

Test Current

|

Short Circuit Current

---|---|---
200MW/250VDC|

1mA

|

250k Ω (load)

| ****

1mA Nominal

200MW/500VDC|

500k Ω (load)

0-1000MW/1000VDC|

1M Ω

1000-2000MW/1000VDC

AC VOLTAGE (40Hz-400Hz)

Range

| Resolution| Accuracy| Input Impedance|

Overload Protection

---|---|---|---|---

750VAC

| 1V| ±1.2% + 10d| 10M Ω|

750Vrms

DC VOLTAGE

Range

| Resolution| Accuracy| Input Impedance|

Overload Protection

---|---|---|---|---

1000VDC

| 1V| ±0.8% + 3d| 10MW|

1000Vrms

RESISTANCE

Range

| Resolution| Accuracy| Max. Open Circuit Voltage|

Overload

Protection

---|---|---|---|---

200 Ω

| 0.1 Ω| ±1% + 2d| 4.5V|

250Vrms

200k Ω

| 0.1k Ω| ±1% + 2d| 3V|

250Vrms

Two-year Warranty

FLIR Systems, Inc. warrants this Extech brand instrument to be free of defects in parts and workmanship for two years from date of shipment (a six- month limited warranty applies to sensors and cables). To view the full warranty text please visit: http://www.extech.com/support/warranties.

Calibration and Repair Services

FLIR Systems, Inc. offers calibration and repair services for the Extech brand products we sell. We offer NIST traceable calibration for most of our products. Contact us for information on calibration and repair availability, refer to the contact information below. Annual calibrations should be performed to verify meter performance and accuracy. Product specifications are subject to change without notice. Please visit our website for the most up-to-date product information: www.extech.com.