Associated Research MEG CHEK 2100 User manual

Α
OWNERS MANUAL

TABLE OF CONTENTS
CHARACTERISTICS & PERFORMANCE 1
SAFETY ......4:. 2 ν.μ 3
PREPARATION. FOR TESTA ου... 4
OPERATING INSTRUCTIONS ........ 5-8
SPECIFICATIONS:
MODEL 2100A Mm eee eee 9
MODEL 2101A See 10
BATTERY INSTALLATION &
OPERATIONAL CHECK:
MODEL 2100Α & 2101A ............. 11
USE OF AC LINE ADAPTOR:
MODEL 2100A & 2101A ............. 12
WARRANTY ....... σ᾿ 13

CHARACTERISTICS
AND PERFORMANCE
The MEG-CHEKS covered in this manual,
are all electronic state-of-the-art technol-
ogy for long trouble free service. Most can
be operated from a 115 volt 50/60 HZ line
when the line adaptor is used.
The high voltage switching power supply for
MEGOHMS is a transformer coupled DC to
DC converter, controlled by a Regulating
Pulse Width Modulator. All control circuitry,
the oscillator, error amplifier, pulse width
modulator, transistor output switches, etc.
are contained on one IC. A voltage regulator
maintains a constant input voltage to the
control systems to compensate for battery
aging orcranking speed. Theamplifier sam-
ples power supply output voltage thru a
feed-back system and maintains output re-
gulation within .25% from no load (open-
circuit)to full load (short-circuit), by control-
ling the pulse width.
For measuring low values of resistance, the
OHMS measuring system receives power
directly from the voltage regulator, main-
taining regulation within .2% from no load to
full load.
Meter zeroing is automatic on all ranges and
needs no adjustment. Through use of preci-
sion range resistors, a linear DC meter
movement and a highly regulated power
supply, superior meter tracking accuracy is
achieved.

On battery powered units, battery voltage is
comparedtotheregulator voltage and when
battery life nears its end, a flashing LOW
BATTERY indicator warns the operator, with
sufficient lead time, that the batteries need
replacing. If ignored, when battery voltage
drops to a point where the regulator begins
to lose control, an under voltage shut-down
system turns the power supply off and no
reading can be taken. However, itis strongly
recommended that the batteries be replaced
as soon as possible once there is a warning
of weak batteries. On generator powered
units, generator voltage is compared to the
regulator voltage and when the generator is
being cranked too slow, a flashing LOW
RPM indicator warns the operator. In all
cases, this assures against incorrect read-
ings since lack of regulation would disturb
calibration of meter zero.
Most models have AC voltage measuring
systems, some have capabilities of measur-
ing DC voltage also. The AC voltage measur-
ing system is average responding with the
scale calibrated in RMS. Input impedance is
approximately 100K Ohms for both the AC
and DC measuring system.
For safety, a bleeder resistor is automati-
cally connected across the test terminals
through an output shorting system when the
TEST switch is released, or when generator
cranking is stopped. This discharges the test
item capacitance when the test is complete.
A guard circuit arrangement on the circuit
board reduces surface leakage influence on
the reading and augments accuracy.

SAFETY
Before preparing for a test and before oper-
ating the equipment, observe all safety rules.
Be sure that safety gear is available and in
good condition. When switches or breakers
are opened for atest, be sure they are locked
out or guards and safety signs are posted.
Always test the disconnected circuit or ap-
paratus for presence of voltage. Remember
that itis possible for voltage to be induced in
the disconnected circuits from proximity to
other high voltage equipment. Always apply
a ground to the disconnected circuits before
and after atest to prevent static charges. Use
rubber gloves when connecting test leads
and when using the MEG-CHEK. Remem-
ber, the MEG-CHEK delivers high voltage
and equipment or cables that are highly
capacitive can store a dangerous amount of
energy after they have been tested. Even
though the MEG-CHEK is equipped with an
automatic discharge system, always ground
the circuit or apparatus after a test is com-
plete and before handling the test leads.
Never handle the test leads when the power
source of the MEG-CHEK is energized.
DO NOT USE THE MEG-CHEK IN AN EX-
PLOSIVE ATMOSPHERE! A slight sparking
of the test leads could occur when connect-
ing or disconnecting, due to any slight
capacitive charge on the circuit or apparatus
to be tested, as could arcing across faulty
insulation.
Never allow any unauthorized personnel in
the area when tests are to be performed.
Roping off the area and posting warning
signs is highly recommended.

PREPARATION FOR TEST
Take equipment or circuits out of service.
Use the MEG-CHEK voltmeter system to
check between terminals and ground to be
sure no voltage is present. The equipment
must be completely disconnected from the
power source for safety and to prevent
serious damage to the insulation resistance
test equipment. Power or distribution cables
must be disconnected at both ends. In the
case of rotating machinery, transformers,
switchgears, etc., disconnect all leads, if
possible, from the unit to be tested. Inspect
the insulation system carefully to determine
exactly what will be included in the test. If
switches or fuse boxes are left in the circuit,
they too will be tested and could influence
readings to a marked degree. The more
equipment that is included in the circuit, the
lower the insulation resistance will be. The
true insulation resistance of the apparatus
that is desired to be tested may be masked
by the parallel influence of other connected
equipment.
Where practical, more significant test re-
sults will be obtained when each phase is
tested separately to ground with all other
phases grounded. This also allows testing
phase to phase for useful comparison in-
formation.

OPERATING INSTRUCTIONS
CAUTION: Make sure that the equipmentto
be tested is de-energized before attempting
to measure its insulation resistance or cir-
cuit resistance. If voltage is present when
the selector switch is in the OHMS or MEG-
OHMS position, the MEG-CHEK may be
severely damaged.
Some instruments are battery operated,
others employ a hand-crank generator.
Most can be operated by a line adaptor fur-
nished with the instrument. To use the line
adaptor, simply plug the adaptor miniature
phone plug into the receptacle on the instru-
ment and plug the adaptor into a 115 volt
outlet. Then follow steps below.
|. TO MEASURE INSULATION
RESISTANCE
1. Check for voltage to make sure equip-
ment has been taken out of service
and no static charge is present.
2. Set the range selector switch on the
proper Megohm range and proper
test voltage range, if the instrument is
equipped with multiple voltage ranges,
for megohm testing.
3. Connect the red and black test leads
to the (+) and (-) terminals respec-
tively. Use of GUARD on instruments
so equipped is optional.
4. For a circuit or phase to ground test,
connect the red test lead to the circuit
or phase to be tested and the black
lead to ground.
5

Fora circuit to circuit
or phase to phase test, connect the
red test lead to one circuit or phase
and the black test lead to the other
circuit or phase.
In both cases it is imperative that the
circuit or phases are isolated from
ground and from each other.
. On battery operated units, depress
the TEST push button.
. After appropriate time lapse, depend-
ing on type of test, read the insulation
resistance on the Megohm scale, mul-
tiplied or divided by the factor indi-
cated by the range selector switch.
. At completion of test, release the
TEST button or stop cranking, depend-
ing on type of instrument being used,
and the output shorting system will
discharge the test item. It is good
safety practice to additionally ground
the circuit with a jumper lead before
disconnecting the test leads.

ur MEASURE CIRCUIT RESISTANCE
. Checkfor voltage to make sure equip-
ment has been taken out of service
and no static charge is present.
. Set the range selector switch on the
OHMS range.
. Connect the red and black test leads
to the (*) and (-) terminals respec-
tively.
. Connect the red test lead to one end
of the circuit to be measured and the
black lead to the other end.
. Read the resistance on the OHMS
scale multiplied by the scale factor
indicated by the range selector switch.
When test is complete, release the
TEST push button or stop cranking
depending on the type of instrument
being used.
TO MEASURE VOLTAGE (V)
1.
Set the range selector switch on the
appropriate voltage measuring range.
Some instruments are for AC mea-
surements only, others have AC and
DC capabilities that require the
AC/DC selector switch to also be set
for the appropriate function.
. Connect the red and black test leads
to the (*) and (-) terminals respec-
tively.
. Connect the test leads, observing
polarity if measuring DC, to the points
where voltage isto be measured. Read
the voltage on the Voltmeter scale.
Operation of the TEST button or crank-
ing of the generator is not required
when measuring voltage.

GUARD CIRCUIT
Some instruments are equipped with a
GUARD terminal and guard circuit that
allows bypassing unwanted leakage current
around the metering circuit. Such unwanted
leakage current may be due to surface leak-
age or floating metallic circuits, such as
found in a multi-winding transformer or
multi-conductor cables, that provide a leak-
age path due to static charges.
This allows measuring insulation resistance
of two specific circuits without influence of
other resistive paths.
The GUARD terminal can be connected to
electrodes that are in contact with the sur-
face of the insulation. However, these elec-
trodes cannot be connected to the circuits
under test, and must be in contact with the
insulation only in order to intercept leakage
current over the surface.
The GUARD terminal may also be connected
to the floating circuits such as transformer
windings not being tested, or circuits in a
multi-conductor cable not being tested.
These windings or circuits must also be iso-
lated from each other and from the windings
or circuits under test.

4
MODEL
2100A
1. Push-To-Test Button 5. Test Leads
2.
AC
Volt,
Ohm.
6.
Low
Battery
In-
Meg-Ohm Meter dicator
3
High
Voltage
&
7.
Selector
Switch,
AC
Return Terminals Volts, Ohms,
4. Guard Circuit Terminals Meg-Ohms.
SPECIFICATIONS:
MEG-CHEK 2100A
MEASURING
RANGES:
CABINETRY:
Megohm
-
200/500/1000/2000
(H/WIL
-
inches)
Ohms
-
20,000
6.38/7.75/6.25
Respective
Test
(H/WIL
-
cm)
Voltage
-
100/250/500/1000
16.2/19.7/15.9
Volts - measuring - 600 rms
POWER
SOURCE:
WEIGHT:
Battery
-
8
D
cells
LBS
-
7.0
Line
Voltage
-
115
volts
KG
3.17
ACCURACY:
Megohms-ohms ` 1°.% of scale length
Volts 3%. of ful! scale
9

=
3.
4.
MODEL
2101A
Push-To-Test Button 5. AC/DC Volt Selector
AC/DC Volt, Ohm, Switch
Meg-Ohm Meter 6. Volt, Ohm Meg-Ohm
High Voltage & Selector Switch
Return Terminal 7. Test Leads
Low Battery Indicator
SPECIFICATIONS:
MEG-CHEK 2101A
MEASURING RANGES: CABINETRY:
Megohm - 200 (H/W/L-inches)
Ohms - 20,000 6.38/7.75/6.25
Respective Test (H/WIL - cm)
Voltage - 500 16.2/19.7/15.9
Volts - measuring - 150/300/600
AC rms 8 DC
POWER SOURCE: WEIGHT:
Battery - 8 D cells LBS - 7.0
Line Voltage - 115 volts KG - 3.17
ACCURACY:
Megohms-ohms - 1'⁄% of scale length
Volts - - 3% of full scale
10

ΩΝ
ΟΡ
T
BATTERY INSTALLATION
MODELS
2100A & 2101A
. Remove the battery tray by turning the two 1⁄4 turn
screws located on the back of the unit.
. Slide the battery tray out.
. Install the batteries, be certain to observe for pro-
per polarity.
. Reverse the above procedure to secure the battery
tray in place.
ERATIONAL CHECK:
Connect the red and black test leads to the (+)
and (—) terminals respectively.
Set the range selector switch to the ohms position
and connect the test leads together.
Press the push-to-test button, the meter pointer
should swing up scale to “Ὁ”.
. Repeat Step 3 with the selector switch in the meg-
ohm position.
. During this check, or during normal operation, if
the low battery indicator remains lit or is flashing,
the batteries are weak and should be replaced.
11

MODELS
2100A & 2101A
These MEG-CHEKS* will properly operate with an
input voltage between 7.5 and 15 volts DC.
All models except 2002A are supplied with a 115 Volt
line adaptor.
On battery operated units, the adaptor can be used
when the batteries are low or to conserve battery life.
12

MEG-CHEK WARRANTY
Models 2100A, 2101A, 2125A
This new Meg-Chek is warranteed to be free from
defects in workmanship and material for one year from
the date of shipment, provided there is no evidence of
modifications, tampering or physical damage.
By-passing any safety systems will void this warranty.
THIS WARRANTY DOES NOT COVER TUBES, BAT-
TERIES OR ACCESSORIES NOT OF ASSOCIATED
RESEARCH MANUFACTURE.
Any unit found defective under this warranty will be
repaired free of charge if returned to the factory prepaid
and insured. -
EXCEPT AS PROVIDED HEREIN, ASSOCIATED
RESEARCH MAKES NO WARRANTIES TO THE PUR-
CHASE OF THIS UNIT AND ALL OTHER WARRAN-
TIES, EXPRESS OR IMPLIED (INCLUDING, WITHOUT
LIMITATION, MERCHANTABILITY OR FITNESS FOR
A PARTICULAR PURPOSE) ARE HEREBY EXCLUD-
ED, DISCLAIMED AND WAIVED.
To avoid delay, before returning the instrument for
repair you must first contact Associated Research for
authorization and shipping instructions.
13

Notes:

Notes:

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60044
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