Universal Enterprise DMEG2 Installation Manual

1-800-547-5740 • Fax: [phone]

www.ueitest.com • email: [e-mail]

DMEG2

INSTRUCTION MANUAL

C o n t r ols and Indicators

1. Rotary Selector Knob: Switches measurement function.

2. Ohms: This is the low resistance or “c o n t i n u i ty” position. Used to
i d e n t i fy low resistance circuits such as motor run and start winding
which may differ by only a few ohms.

3. 200MΩ (250, 500V): In this position approximately 500 V DC is
applied to the circuit under test when the TEST switch is pressed. The
0 - 2 0 0 M Ω range is used primarily to test insulation resistances which
have begun to degra d e .

4. 200MΩ (1000V): In this postilion approximately 1000 V DC
is applied to the circuit under test when the TEST switch is
pressed. This is the range which is normally used for preventive
maintenance measurements on electrical equipment. Insulation
resistance values in this application typically exceed 100MΩ.

5. ON/OFF switch: Slide the switch forward to turn the instrument
on, slide it back to turn the instrument off.

6. Test Switch: The TEST switch is normally OFF, spring loaded,
momentary action switch which “turns on” the DMEG2. The
momentary action is a safety feature. The test voltage generated
by the DMEG2 is automatically discharged when the TEST
switch is released.

Introduction

The DMEG2 Insulation Resistance Tester is a completely portable,
self-contained, four range, solid state test instrument.

Power is provided by eight internal, standard 1.5V, size AA (ABI)
batteries. An electronically regulated constant voltage generator
supplies the test voltage for the 2000MΩ range (1000V) and the
2000MΩ range (500V), and the 2000MΩ range (250V). The internal
batteries supply the power directly for the 0-200Ω low resistance range.

This rugged precision instrument can locate intermittent shorts,
defective electrical connections, insulation breakdowns or conductor
failures due to the effects of temperature, moisture, abrasion, corrosion,
or other environmental conditions.

One of the most effective applications, and one of the most overlooked
applications for the DMEG2 is in the field of preventive maintenance.
For example, when the insulation properties of a hermetic compressor
motor begins to fail it usually does so gradually at first. A routine,
periodic monitoring of the insulation resistance of the start and run
winding will usually show evidence of a potential burn out well in
advance of the actual occurrence.

Features include

• Battery operated

• Automatic circuit discharge

• Solid state circuitry

• LCD display

• Automatic zero adjust

• Four ranges

• Automatic low battery indication

• Audible warning signal

• Live circuit indicator

Safety Notes

Before using this instrument, read all safety information carefully. In
this manual the word "WARNING" is used to indicate conditions
or actions that may pose physical hazards to the user. The word
"CAUTION" is used to indicate conditions or actions that may
damage this instrument.

International Symbols

DMEG2-MAN P. 1

1

2

Electrical shock can cause an unstable heart rhythm
that may need medical attention.

3

4

5

6

DC Devices

Independent insulation tests may be carried out between the electrical
sections of a DC generator, or motor, and ground. Separate the brushes
from the commutator (Fig. 2) to isolate the brushes and field coil
functions from the rotor. These separated sections may be easily tested
independently of each other. This does not apply, however, when an
overall insulation test is intended. In this case the brushes remain in
contact with the commutator so that the three sections (brushes, coils
and rotor) may be tested integrally.

Hermetic Compressor

Most hermetic compressor utilize a three terminal block for making
electrical connections to the sealed unit (Fig. 3). The connection may be
made by an “umbilical” cord or a screw terminal, but the most common
connection method is usually with a relay that pushes onto the S and M
terminals and an overload protector that pushes onto the C terminal.
(Refer to the manufacturer’s manual)

Shut off power to the unit under test and remove the connections to
the compressor terminal block. Connect the red test lead of the DMEG2
tot he C terminal and the black test lead to the frame, or ground.
Measure the insulation resistance. Low values of insulation resistance
may indicate the presence of contaminated refrigerant. Refer to the
chapter on interpreting test results.

Winding continuity may be checked by setting the SELECTOR switch on
OHMS. Check the start and run winding by measuring the resistance
between the C terminal and the S or M terminal.

Operating Instructions

CAUTION!

Observe all safety precautions when the CONTROL switch is set to
either the 2000MΩ (500V) or the 2000MΩ (1000V) position. Connect
the DMEG2 test leads to the circuit under test before operating the
TEST switch. DO NOT touch the battery clip ends of the test leads when
the TEST switch is in the TEST position. Some electrical equipment,
especially cables, may retain an electrical charge when disconnected
from the line. It is a good practice to discharge such equipment with
grounding straps, or other suitable devices, before touching or making
connections. The DMEG2 automatically discharges the test circuits when
the spring loaded TEST switch is released.

WARNING!

Remove all power to the circuit under test when making resistance
measurements. If any voltage is present in the test circuit an erroneous
reading will result.

Motors and Generators

Disconnect the motor from the line either by opening the main switch
or by disconnecting the wires at the motor terminals. if the main switch
is opened and measurements are made at the switch contacts, then the
insulation resistance of all components between switch and motor will
be measured simultaneously. If a fault is indicated it will be necessary to
test each section separately.

AC Devices

The basic test is to connect the red test lead of the DMEG2 to one of
the motor terminals, or wire, and the black test lead to the frame or
housing (Fig. 1). Start and run winding may be checked for correct
resistance by setting the SELECTOR switch to OHMS and connecting
one test lead to the common winding terminal and the other test lead
to the start or run terminal.

DMEG2-MAN P. 2

(Fig 2)

(Fig 1)

(Fig 3)