AEMC 1020 User manual

Megohmmeters
Model 1020
Model 1025
Chauvin Arnoux,Inc. d.b.a. AEMC® Instruments
99-MAN-100110 Rev 0308/18

Megohmmeters
Model 1020
Model 1025
USER MANUAL
!
MΩ
500 V
Ω
+ Earth
- Line
TEST
TIMER
DATA HOLD
Man. 3 Min.
1000 V
MΩ
250 V
VAC
~
/ΩVAC
~
OFF ON
M Ω
MEGOHMMETER
MODEL 1025

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:
AEMC®Instruments
by Chauvin Arnoux, Inc.
99-MAN-100110
2nd Revision
Printed 07/97

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 (MΩRange) . . . . . . . . . . . . . . . . . .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 per-
sonnel 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 per-
forming or assisting in the tests must employ all safety precau-
tions 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.
2Megohmmeter Models 1020 and 1025
International Electrical Symbols
This symbol signifies CAUTION! and requests that the user
refer to the user manual before using the meters.
!

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, giv-
ing a detailed description of the damages. Save the damaged pack-
ing 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-oper-
ated, 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 VAC range
for safety voltage check.
The press-to-test button has an associated locking feature for contin-
uous 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
4Megohmmeter 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
Megohmmeter Models 1020 and 1025 5
*Accuracies are at 23° C ± 5° C, below 80% RH

CONTINUITY TESTS (Ω)
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.
6Megohmmeter Models 1020 and 1025
HO
*Accuracies are at 23° C ± 5° C, below 80% RH
~

Megohmmeter Models 1020 and 1025 7
Ω
Ω
Ω
Ω
Ω
Model 1020
1. Digital Display
2. Data Hold Switch
3. Manual and Lock Switch
(locks power on for 3 minutes)
4. Press-to-Test Button
5. Range Selector Switch
6. Test Terminals
Figure 1

8Megohmmeter Models 1020 and 1025
Model 1025
!
MΩ
500 V
Ω
+ Earth
- Line
TEST
TIMER
DATA HOLD
Man. 3 Min.
1000 V
MΩ
250 V
VAC
~
/ΩVAC
~
OFF ON
M Ω
MEGOHMMETER
MODEL 1025
1. Digital Display
2. Data Hold Switch
3. Manual and Lock Switch
(locks power on for 3 minutes)
4. Press-to-Test Button
5. Range Selector Switch
6. Test Terminals
Figure 2

Safety Check - Voltage Test
NOTE: Make sure the jacks are firmly inserted into the megohm-
meter 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 per-
form 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.
Insulation Resistance Testing (MΩRange)
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
MΩ
+ Earth
- Line
/ΩVAC
~
Figure 3

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 resis-
tance 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 recommend-
ed 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 = Dielectric Absorption Ratio (DAR)
Insulation resistance @ 30s
This test is useful to increase the accuracy of spot testing. In gener-
al, a ratio of 1.5 or better should be required. A ratio below this indi-
cates that repair is probably needed.
10 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 spe-
cific 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
Figure 4 shows the connections to measure the insulation of one con-
ductor to the other conductors. The cable should be disconnected at
both ends to avoid leakage through switchboards and panels.
12 Megohmmeter Models 1020 and 1025
!
MΩ
500 V
Ω
+ Earth
- Line
TEST
TIMER
DATA HOLD
Man. 3 Min.
1000 V
MΩ
250 V
VAC
~
/ΩVAC
~
OFF ON
M Ω
MEGOHMMETER
MODEL 1025
– +
Conductor Under Test
Cable Insulation
Figure 4

Figures 5 and 6 show the connections for testing insulation from a
supply conductor to ground (motor frame).
Megohmmeter Models 1020 and 1025 13
!
MΩ
500 V
Ω
+ Earth
- Line
TEST
TIMER
DATA HOLD
Man. 3 Min.
1000 V
MΩ
250 V
VAC
~
/ΩVAC
~
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
~
/ΩVAC
~
OFF ON
Figure 5
Figure 6
Conductor Under Test
Cable Insulation
Conductor Under Test
Cable Insulation

Figure 7 shows the connec-
tions to a transformer (light-
ing 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 wind-
ing grounded.
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 resis-
tance to ground at the same time.
By removing the jumpers, read-
ings can be made between the
individual conductors and
ground.
14 Megohmmeter Models 1020 and 1025
Ω
- +
MEGOHMMETER
MODEL 1020
MΩ
500 V
Ω
+ Earth
- Line
TEST
TIMER
DATA HOLD
Man. 3 Min. MΩ
250 V
VAC
~
/ΩVAC
~
OFF ON
Ω90.6
– +
MEGOHMMETER
MODEL 1020
MΩ
500 V
Ω
+ Earth
- Line
TEST
TIMER
DATA HOLD
Man. 3 Min. MΩ
250 V
VAC
~
/ΩVAC
~
OFF ON
Figure 7
Figure 8
Tested
Winding
Transformer
Grounding Lug
Jumpers

INSULATION RESISTANCE MEASUREMENTS ON MOTORS
Figure 9 shows reading
the resistance to ground of
a three-phase motor wind-
ing. Since the three-phase
motors are internally con-
nected, it is only neces-
sary to connect one lead to
the motor lead and the
other lead to the motor
frame as shown.
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
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”.
Megohmmeter Models 1020 and 1025 15
!
MΩ
500 V
Ω
+ Earth
- Line
TEST
TIMER
DATA HOLD
Man. 3 Min.
1000 V
MΩ
250 V
VAC
~
/ΩVAC
~
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
~
/ΩVAC
~
OFF ON
Figure 10
Figure 9

Figure 11 shows connections
for testing insulation from a
supply conductor in a switch-
box to ground (motor frame).
An identical test may be car-
ried out from the motor
starter.
Continuity Measurements
Once it has been verified that no voltage is present, the continuity
check may be performed.
Set the switch to the Ωposition.
Connect the red lead in the +earth position and the black lead in the
middle jack position.
16 Megohmmeter Models 1020 and 1025
!
MΩ
500 V
Ω
+ Earth
- Line
TEST
TIMER
DATAHOLD
Man. 3 Min.
1000 V
MΩ
250 V
VAC
~
/ΩVAC
~
OFF ON
M Ω
MEGOHMMETER
MODEL 1025
– +
Figure 11
MΩ
+ Earth
- Line
/ΩVAC
~
Figure 12

When the resistance is less than 100Ωit will be indicated by a con-
tinuous beeper.
If an open circuit has been detected the display will read:
Resistance Measurements
Set the switch to the Ωposition.
Connect the red lead in the +earth position and the black lead in the
middle jack position.
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 17
MΩ
+ Earth
- Line
/ΩVAC
~
Ω
HOLD
Ω
HOLD
Figure 14
Figure 15
Figure 13