Aemc instruments 1025, 1020 User Manual

Megohmmeters
Model 1020
Model 1025

Chauvin Arnoux, Inc. d.b.a. AEMC® Instruments

99-MAN-100110 Rev 02 06/97

Megohmmeters

!

MΩ

500 V

Ω

+ Earth

- Line

TEST

TIMER

DATA HOLD

Man.

3 Min.

1000 V

MΩ

250 V

VAC

~

/ΩV

AC

~

OFF

ON

M Ω

MEGOHMMETER

MODEL 1025

Model 1020
Model 1025

USER MANUAL

Owner’s Record

The serial number for the Megohmmeter Model 1020 or Model 1025
is located on the back of the instrument. Please record this number
and purchase date for your records.

MEGOHMMETER MODEL 1020
CATALOG # 2111.91
SERIAL #:
PURCHASE DATE:
DISTRIBUTOR:

MEGOHMMETER MODEL 1025
CATALOG # 2111.87
SERIAL #:
PURCHASE DATE:
DISTRIBUTOR:

99-MAN-100110
2nd Revision
Printed 07/97

AEMC®Instruments
by Chauvin Arnoux, Inc.

Table of Contents

Warning . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2

International Electrical Symbols . . . . . . . . . . . . . . . . . . . . . . . . . .2

Receiving Your Shipment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3

Packaging . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3

Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3

Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4

Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5

Safety Check/Voltage Test . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .9

Insulation Resistance Testing (MΩ Range) . . . . . . . . . . . . . . . . . .9

Test Voltage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .9

Spot Testing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .10

Ratio Testing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .10

For Successful Insulation Resistance Testing . . . . . . . . . . .11

Insulation Measurement - Connections . . . . . . . . . . . . . . .12

Insulation Resistance Measurements on Motors . . . . . . . .15

Continuity Measurements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .16

Resistance Measurements . . . . . . . . . . . . . . . . . . . . . . . . . . . . .17

Data Hold . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .18

Timer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .18

Maintenance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .19

Repair and Calibration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .20

(North/South America, Australia, New Zealand) . . . . . . . . .20

(Europe, Asia, Africa) . . . . . . . . . . . . . . . . . . . . . . . . . . . .21

Technical and Sales Assistance . . . . . . . . . . . . . . . . . . . . . . . . .22

Limited Warranty . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .23

Warning

!

These safety warnings are provided to ensure the safety of per­sonnel and proper operation of the instrument.

• Read this instruction manual completely before attempting to
use or service this instrument and follow all safety information.

• Safety is the responsibility of the operator!

• Tests are to be carried out only on dead circuits! Check for live
circuits before making resistance measurements (safety
check).

• Always make connections from the instrument to the circuit
under test.

• The Megohmmeter Models 1020 and 1025 are sources of high
voltage, as is the sample connected to them. All persons per­forming or assisting in the tests must employ all safety precau­tions to prevent electrical shock to themselves and to others.

• AEMC®considers the use of rubber gloves to be an excellent
safety practice even if the equipment is properly operated and
correctly grounded.

• When testing capacitance samples, make sure that they have
been properly discharged and that they are safe to touch.
Dielectric insulation samples should be short-circuited for at
least five times the amount of time they were energized.

• Never open the back of the instrument while connected to any
circuit or input.

International Electrical Symbols

This symbol signifies CAUTION! and requests that the user
refer to the user manual before using the meters.

2

Megohmmeter Models 1020 and 1025

Receiving Your Shipment

Upon receiving your shipment, check to be sure that the contents
agree with the packing slip. Notify your distributor at once of any
shortages. If the equipment appears to be damaged, file a claim
immediately with your carrier, and notify your distributor at once, giv­ing a detailed description of the damages. Save the damaged pack­ing container to substantiate your claims.

Packaging

Megohmmeters Model 1020 (Cat. #2111.91) and Model 1025 (Cat.
#2111.87) are shipped with a carrying case, two color-coded leads,
six 1.5 V “AA” batteries, and an instruction manual.

Description

Model 1020 and Model 1025 are compact, light-weight, battery-oper­ated, digital megohmmeters. The Model 1020 tests at 250 V and 500
V up to 200 MΩ. The Model 1025 adds an additional voltage range of
1000 V, and measures up to 2000 MΩ.

The Models 1020 and 1025 also feature a continuity test range with
an audible beeper for resistances under 100Ω, and a 600 V AC range
for safety voltage check.

The press-to-test button has an associated locking feature for contin­uous tests up to three minutes, eliminating the need to hold down the
button manually.

Other features include a large 3-1/2 digit LCD, automatic zero, data
hold switch, and low battery indicator. These light-weight, easy-to-use
megohmmeters can be used for most commonly performed insulation
tests, such as on cables, switch gear, motors, DC generators, power
tools, and small appliances.

The Models 1020 and 1025 include test leads, batteries, carrying
case, and user manual.

Megohmmeter Models 1020 and 1025

3

Models 1020/1025 Features

• Model 1020 measures insulation at 250 and 500 V.

• Model 1025 measures insulation at 250, 500, and 1000 V.

• Continuity test

• Continuity beeper

• 600 V AC safety test voltage range

• Large, easy-to-read digital display

• Data hold switch

• Three-minute “lock-on” test button for hands-free operation

• Automatic discharge when test button is released

• Low battery indication

4

Megohmmeter Models 1020 and 1025

Models 1020/1025 Specifications

ELECTRICAL SPECIFICATIONS

INSULATION TESTS

DC Test Voltage:

250 V and 500 V (Model 1020)
250, 500, 1000 V (Model 1025)

Megohm Range:

0.1 to 200 MΩ (Model 1020 and 1025)
1 to 2000 MΩ (Model 1025 @ 1000 V)

Resolution:

250 and 500 V : 0.1 MΩ
1000 V : 1 MΩ

Short Circuit Current:

0.4 mA max. at 250 V

0.9 mA max. at 500 V

1.7 mA max. at 1000 V

Accuracy:*

0.1 to 1000 MΩ: 3% of reading ± 3 digits
1000 to 2000 MΩ: 5% of reading ± 3 digits (Model 1025 only)

Test Voltage Generation:

Solid state circuitry generating test voltage (± 10%).

RESISTANCE TESTS (Ω)

Range: 0.1 to 200Ω
Accuracy:* 1% of reading ± 2 digits
Maximum Open Circuit Voltage: 3.3 V
Overload Protection: 500V DC/AC

*Accuracies are at 23° C ± 5° C, below 80% RH

Megohmmeter Models 1020 and 1025

5

CONTINUITY TESTS (Ω)

HO

Range: 0 - 100Ω (with display and beeper)
Resolution: 0.1Ω
Operation Resistance: < 100Ω
Max. Open Circuit Voltage: 3.2 V
Overload Protection: 500 V DC/AC

VOLTAGE TESTS SAFETY CHECK (VAC)

~

Range: 0 - 600 V AC
Resolution: 1 V
Accuracy:* 0.8% of reading ± 3 digits
Input Impedance: 10 MΩ

GENERAL SPECIFICATIONS

Power Supply: Six 1.5 V “AA” batteries
Low Battery Indication: Indicator on LCD
Display: 3-1/2 digit LCD, 0.65” height
Overrange Indicator: Highest digit of (1) displayed
Operating Temperature: 32° to 104°F (0° to 40°C)
Storage Temperature: 14° to 140°F (-10° to 60°C)
Operating Humidity: 0 - 80% RH
Storage Humidity: 0 - 70% RH
Dimensions: 6.5 x 3.9 x 2.2” (165 x 100 x 57mm)
Weight: 1.1 lb (500 g) approx.

*Accuracies are at 23° C ± 5° C, below 80% RH

6

Megohmmeter Models 1020 and 1025

Ω

Ω

Ω

Ω

Ω

Model 1020

Figure 1

1. Digital Display

2. Data Hold Switch

3. Manual and Lock Switch
(locks power on for 3 minutes)

Megohmmeter Models 1020 and 1025

4. Press-to-Test Button

5. Range Selector Switch

6. Test Terminals

7

Model 1025

!

MΩ

500 V

Ω

+ Earth

- Line

TEST

TIMER

DATA HOLD

Man.

3 Min.

1000 V

MΩ

250 V

VAC

~

/ΩV

AC

~

OFF

ON

M Ω

MEGOHMMETER

MODEL 1025

Figure 2

1. Digital Display

2. Data Hold Switch

3. Manual and Lock Switch
(locks power on for 3 minutes)

8

4. Press-to-Test Button

5. Range Selector Switch

6. Test Terminals

Megohmmeter Models 1020 and 1025

Safety Check - Voltage Test

MΩ

+ Earth

- Line

/ΩVAC

~

NOTE: Make sure the jacks are firmly inserted into the megohm­meter prior to performing any electrical tests!

Before measuring insulation resistance, confirm that the sample is
fully discharged (particularly in dielectric and capacitance samples),
and that the sample is not connected to an energized circuit. To per­form the voltage test:

1) Insert the red lead into the +earth position and the black lead in the
middle jack position.

2) Set the range selection switch to the VAC position.

3) Connect to the sample
under test.

4) Press the test button.

Figure 3

Insulation Resistance Testing (MΩ Range)

After checking for a live circuit (see Safety Check), connect the
megohmmeter. See Figures 4 through 11 for examples.

TEST VOLTAGE

No published standard tells which voltage to choose for any given
winding. However, published recommendations are summarized as
follows:

Rated Voltage of Motor Test Voltage

Below 115 250 V

115 250 V or 500 V
230 500 V
460 500 V or 1000 V

Megohmmeter Models 1020 and 1025

9

SPOT TESTING

As a general rule in spot testing, test voltage should be applied until
no variation in reading is noted for 15 seconds, or applied for a fixed
60 seconds. What minimum value should be measured? The IEEE
standard No. 43-1974 states that it is impossible to specify the value
of insulation resistance at which a winding will fail electrically, but on
motors, minimum readings generally stated are:

Rated Voltage R Minimum

250 or less 2 MΩ

460 2 MΩ

There is no fixed figure for determining what is good and bad in resis­tance readings, but a good guide would be 1 megohm for every 100
applied operating volts, as a minimum figure. This applies to motors
and transformers. When the insulation resistance gets this low, an
electrical breakdown can be expected at any time, and rewinding or
replacing should be considered.

It is not unusual for a winding to be 10 to 100 times the recommend­ed minimum value (IEEE standard 43-1974: Recommended Practice
for Testing Insulation Resistance of Rotating Machinery), but this
varies with temperature and humidity.

RATIO TESTING

In time resistance testing (Dielectric Absorption Ratio), readings are
taken at 30 and 60 seconds to obtain the dielectric absorption ratio.

Insulation resistance @ 60s
Insulation resistance @ 30s

This test is useful to increase the accuracy of spot testing. In gener­al, a ratio of 1.5 or better should be required. A ratio below this indi­cates that repair is probably needed.

10

= Dielectric Absorption Ratio (DAR)

Megohmmeter Models 1020 and 1025

Remember, a DC insulation test may be used for acceptance testing,
but is more commonly used to check the gradual deterioration of
equipment over its life. Consult your equipment manufacturer for spe­cific test or test voltage if not known.

Insulation resistance decreases with moisture, temperature and age and
should be recorded over time at a given temperature and corrected.

FOR SUCCESSFUL INSULATION RESISTANCE TESTING

• Check with the equipment manufacturer for factory insulation
resistance readings.

• Do not rely on insulation resistance testing alone as proof of
winding conditions.

• Do not expect the same value for all parts of all machines.

• Observe consistent test time duration, recognizing that total
current through insulation under test will vary with time.

• Correct all readings properly to a standard reference temperature
(see IEEE Std. #43-1974, Temperature Correction Curve).

• Know what you are testing. Isolate the piece of equipment from
other circuitry.

• Watch trends rather than relying on single “spot” readings.

Megohmmeter Models 1020 and 1025

11

INSULATION MEASUREMENT - CONNECTIONS

!

MΩ

500 V

Ω

+ Earth

- Line

TEST

TIMER

DATA HOLD

Man.

3 Min.

1000 V

MΩ

250 V

VAC

~

/ΩV

AC

~

OFF

ON

M Ω

MEGOHMMETER

MODEL 1025

– +

Figure 4 shows the connections to measure the insulation of one con­ductor to the other conductors. The cable should be disconnected at
both ends to avoid leakage through switchboards and panels.

Conductor Under Test

Cable Insulation

Figure 4

12

Megohmmeter Models 1020 and 1025

Figures 5 and 6 show the connections for testing insulation from a

!

MΩ

500 V

Ω

+ Earth

- Line

TEST

TIMER

DATA HOLD

Man.

3 Min.

1000 V

MΩ

250 V

VAC

~

/ΩV

AC

~

OFF

ON

M Ω

MEGOHMMETER

MODEL 1025

– +

Ω

– +

MEGOHMMETER

MODEL 1020

MΩ

500 V

Ω

+ Earth

- Line

TEST

TIMER

DATA HOLD

Man.

3 Min.

MΩ

250 V

VAC

~

/ΩV

AC

~

OFF

ON

supply conductor to ground (motor frame).

Conductor Under Test

Cable Insulation

Figure 5

Conductor Under Test

Cable Insulation

Figure 6

Megohmmeter Models 1020 and 1025

13

Figure 7 shows the connec-

Ω

- +

MEGOHMMETER

MODEL 1020

MΩ

500 V

Ω

+ Earth

- Line

TEST

TIMER

DATA HOLD

Man.

3 Min.

MΩ

250 V

VAC

~

/ΩV

AC

~

OFF

ON

Ω90.6

– +

MEGOHMMETER

MODEL 1020

MΩ

500 V

Ω

+ Earth

- Line

TEST

TIMER

DATA HOLD

Man.

3 Min.

MΩ

250 V

VAC

~

/ΩV

AC

~

OFF

ON

tions to a transformer (light­ing or distribution). Make
sure that the switches
and/or circuit breakers on
both sides are open. Check
the high voltage winding to
ground, low voltage to
ground, and the resistance
between them with no wind­ing grounded.

14

Jumpers

Figure 8

Tested
Winding

Transformer
Grounding Lug

Figure 7

Figure 8 shows the connections
for measuring the insulation of a
three-phase line to ground by
connecting the jumpers between
phases. This gives a reading of
all conductors at once. If a load
such as a motor, heater, etc., is
attached to the other end of the
line, it will read the load resis­tance to ground at the same time.
By removing the jumpers, read­ings can be made between the
individual conductors and
ground.

Megohmmeter Models 1020 and 1025

INSULATION RESISTANCE MEASUREMENTS ON MOTORS

!

MΩ

500 V

Ω

+ Earth

- Line

TEST

TIMER

DATA HOLD

Man.

3 Min.

1000 V

MΩ

250 V

VAC

~

/ΩV

AC

~

OFF

ON

M Ω

MEGOHMMETER

MODEL 1025

– +

Ω

– +

MEGOHMMETER

MODEL 1020

MΩ

500 V

Ω

+ Earth

- Line

TEST

TIMER

DATA HOLD

Man.

3 Min.

MΩ

250 V

VAC

~

/ΩV

AC

~

OFF

ON

Figure 9 shows reading
the resistance to ground of
a three-phase motor wind­ing. Since the three-phase
motors are internally con­nected, it is only neces­sary to connect one lead to
the motor lead and the
other lead to the motor
frame as shown.

Figure 9

Figure 10 shows the windings of
a three-phase motor separated.
Sometimes this can be done at
the lead terminals, while other
times the end bells must be

Megohmmeter Models 1020 and 1025

Figure 10

removed to get at the lead wires
of the coils. By connecting the
megohmmeter as shown, the
phase insulation resistance
value can now be determined.
Read between phases “A” and
“B”, then “B” and “C”, then “C”
and “A”.

15

Figure 1 1 shows connections

!

MΩ

500 V

Ω

+ Earth

- Line

TEST

TIMER

DATA HOLD

Man.

3 Min.

1000 V

MΩ

250 V

VAC

~

/ΩV

AC

~

OFF

ON

M Ω

MEGOHMMETER

MODEL 1025

– +

MΩ

+ Earth

- Line

/ΩVAC

~

for testing insulation from a
supply conductor in a switch­box to ground (motor frame).
An identical test may be car­ried out from the motor
starter.

Figure 11

Continuity Measurements

Once it has been verified that no voltage is present, the continuity
check may be performed.

Set the switch to the Ω position.
Connect the red lead in the +earth position and the black lead in the

middle jack position.

16

Figure 12

Megohmmeter Models 1020 and 1025

When the resistance is less than 100Ω it will be indicated by a con-

MΩ

+ Earth

- Line

/ΩVAC

~

Ω

HOLD

Ω

HOLD

tinuous beeper.
If an open circuit has been detected the display will read:

Figure 13

Resistance Measurements

Set the switch to the Ω position.
Connect the red lead in the +earth position and the black lead in the

middle jack position.

Figure 14

The instrument has a measurement range of 0.1 to 200Ω
Connect the leads to the device under test.
If an open circuit has been detected the display will read:

Megohmmeter Models 1020 and 1025

Figure 15

17

Data Hold

Will hold last measured value in memory when the Data Hold position
is in the “ON” position. NOTE: You must hold down the yellow test
button to keep the value displayed. The value in memory will still be
displayed if leads are disconnected as long as the yellow test button
is depressed.

Timer

The instrument may be used in a “hands-free operation” by moving
the timer switch to the three minute position and then pressing the
yellow test button. If the yellow test button is pressed when the switch
is in the three minute position it will shut the instrument off. NOTE:
After three minutes all data will be lost! If a DAR (Dielectric Absorption
Ratio) test is performed the user will have to record the value after 30
seconds and 60 seconds.

Insulation resistance @ 60s
Insulation resistance @ 30s
CAUTION: The timer will keep the output leads energized for three

minutes. After three minutes the display will go blank and all mea­sured data will disappear.

This instrument was not designed to perform a Polarization Index (PI)
Test because the test voltage cannot be locked for 10 minutes. If a PI
Test is required, the user will have to hold down the test button and
record the readings at 1 minute and 10 minutes.

Insulation resistance @ 10 min
Insulation resistance @ 1 min

= Dielectric Absorption Ratio (DAR)

= Polarization Index (PI)

18

Megohmmeter Models 1020 and 1025

Maintenance

Battery Replacement

Replace batteries only when the megohmmeter is not connected to a
sample and OFF. (including Timer to Man. position).

When battery voltage is not sufficient the low “BT” symbol will be dis­played.

Remove the screw from the middle of the instrument and remove the
back cover.

Replace the 6 “AA” batteries.
Reinstall the back cover and screw to secure the back cover.

Megohmmeter Models 1020 and 1025

19

Repair and Calibration

(North/South America, Australia, New Zealand)

To guarantee that your instrument complies with the factory specifi­cations, we recommend that the Megohmmeter Models 1020 and
1025 be submitted to our factory service center at one year intervals
for recalibration, or as required by other standards.

For instrument repair and/or calibration, please call our USA factory,
toll-free, at (800) 945-AEMC (800)-945-2362):

Chauvin Arnoux, Inc.
d.b.a. AEMC®Instruments
15 Faraday Drive
Dover, NH 03820 USA
Tel: [phone]

[phone]
Fax: [phone]

www.aemc.com

(Or contact your authorized distributor.)

20

Megohmmeter Models 1020 and 1025

Repair and Calibration

(Europe, Asia, Africa)

To guarantee that your instrument complies with the factory specifi­cations, we recommend that the Megohmmeter Models 1020 and
1025 be submitted to our factory service center at one year intervals
for recalibration, or as required by other standards.

For instrument repair and/or calibration, please call our French factory:

Manumesure - Reux
14130 Pont l’Evêque
France
Tel: [phone]
Fax: [phone]

www.aemc.com

(Or contact your authorized distributor.)

Megohmmeter Models 1020 and 1025

21

Technical and Sales Assistance

(North/South America, Australia, New Zealand)

If you are experiencing any technical problems, or require any assis­tance with the proper use or application of this instrument, please call
our technical hotline:

Chauvin Arnoux, Inc.
d.b.a. AEMC® Instruments

200 Foxborough Blvd.
Foxborough, MA 02035 USA

Tel: [phone]

[phone]

Fax: [phone]

www.aemc.com

Technical and Sales Assistance

(Europe, Asia, Africa)

If you are experiencing any technical problems, or require any assis­tance with the proper use or application of this instrument, please call
our technical hotline:

Chauvin Arnoux
190, rue Championnet
75876 Paris Cedex 18 - France
Tel: [phone]
Fax: [phone]

www.aemc.com

22

Megohmmeter Models 1020 and 1025

Limited Warranty

The Megohmmeter Models 1020 and 1025 are warranted to the
owner for a period of 1 year from the date of original purchase against
defects in manufacture. This limited warranty is given by AEMC
Instruments, not by the distributor from whom it was purchased. This
warranty is void if the Megohmmeter Model 1020 or 1025 has been
tampered with, abused or if the defect is related to service not per­formed by AEMC®Instruments.

What AEMC®Instruments Will Do:

1 year period, you may return the Megohmmeter Model 1020 or 1025
to us for repair or replacement free of charge, provided we have your
REGISTRATION CARD on file. AEMC®Instruments will, at its option,
repair or replace the faulty material.

Note: If a card is not on file, we will require a dated proof of purchase
as well as your REGISTRATION CARD accompanied by the defec­tive material.

What You Must Do:

First obtain a return authorization by phone or by fax
from AEMC®Instruments, then return the Megohmmeter Model 1020 or
1025, indicating place and date of purchase, with a written explanation
of the reason for return. Return material, postage pre-paid to:

Chauvin Arnoux, Inc.
d.b.a. AEMC®Instruments
Service Department
15 Faraday Drive
Dover, NH 03820 USA
Tel: [phone]
[phone]
Fax [phone]

Caution: To protect against in-transit loss, we recommend you
insure your returned material.

For full warranty coverage, please read the Warranty Card which is
affixed to the Warranty Registration Card. Please keep the Warranty
Card with your records.

If a malfunction occurs within the

®

Megohmmeter Models 1020 and 1025

23

NOTES

24

Megohmmeter Models 1020 and 1025

Megohmmeter Models 1020 and 1025

25