KYORITSU KEW 3121A User manual

KEW 3121A, 3122A, 3123A
KEW3121A, 3122A KEW3123A
INSTRUCTION MANUAL
HIGH VOLTAGE INSULATION TESTER

CONTENTS
Page
1．Safety warnings …………………………………………………1
2．Features …………………………………………………………2
3．Specifications ………………………………………………3〜4
4．Instrument Layout ………………………………………………5
5．Operating Instructions …………………………………………6
5-1．Mechanical Zero Adjustment ……………………………6
5-2．Battery Check ……………………………………………6
5-3．Insulation Resistance Measurement ……………………7
5-4．Continuous Measurement ………………………………7
5-5．Use of Guard Terminal ……………………………………8
6．Battery Replacement ……………………………………………9
7．Accessories and options ………………………………………9
7-1. Metal part for Line Probe, and replacement ……………9
7-2. How to use the adaptor for recorder …………………10
8．How to fix the Meter to the Hard case ………………………11
9．Cleaning Meter Cover …………………………………………12

−1 −
1. Safety warnings
Please read through these operating instructions before using the
instrument to avoid any dangers such as electrical shock and to
ensure safe operation of the instrument.
Pay particular attention to all WARNING and CAUTION in this
instruction manual. WARNING indicates warnings to avoid electrical
shock and CAUTION indicates cautions to avoid damage to the
instrument.
#WARNING
●This instrument cannot test live conductors. Ensure that the
circuit to be tested is powered off before performing a test.
●Never open the Battery cover or remove the Instrument panel
during a measurement.
●Confirm that the Rotary switch is at the OFF position, and then
connect the test leads.
●Do not attempt to make measurement in the presence of
flammable gasses. Otherwise, the use of the instrument may
cause sparking, which can lead to an explosion.
●Never attempt to make any measurement if any abnormal
conditions, such as a broken cover or exposed metal parts are
present on the Instrument or test leads.
●Set the Function switch to OFF position after use, and ensure
the Test button is released and unlocked.
#CAUTION
●Do not expose the instrument to direct sunlight, high
temperatures, humidity or dew.
●Never leave the instrument in the environment of 60˚C or
higher temperatures.
●Do not use the instrument if it or test lead is wet.
●Remove the batteries if the instrument is to be stored and will
not be in use for a long period.
●Use a damp cloth with neutral detergent or water for cleaning
the instrument. Do not use abrasives or solvents.

−2 −
2. Features
● Battery powered, the instruments test insulation up to
100000MΩat 2500V for KEW 3121A, 200000MΩat 5000V
for KEW 3122A and 200GΩat 5000V and 400GΩat 10000V
for KEW 3123A.
● Suited for heavy duty electrical maintenance and servicing of
industrial installations, cables, transformers, generators and
switchgear where high voltage insulation tests are required.
● Dual scales for low and high ranges which change
automatically. Colour coded scales for easy reading plus
LED's that illuminate in matching colour.
● Drip proof construction. The case is sealed with rubber
gaskets to protect internal circuit against rain.
● Hard carrying case furnished as standard accessory. Houses
both instrument and test leads in compact form. Made of
plastic, it is highly water resistant.
● Designed for low power consumption. Since the maximum
current consumption is 90mA eight pieces of 1.5V SUM-3（or
equivalent ）permit about 6 hours of continuous operation
even when the instrument is used on maximum load or twice
longer on minimum load.
● Rated output voltage is maintained down to 100MΩfor KEW
3121A, 200MΩfor KEW 3122A and 0.2GΩ/0.4GΩfor KEW
3123A. This permits accurate measurements of low insulation
resistance.
● Optional adapter MODEL8324 is available for connection to
recorder and enables cable insulation monitoring.

−3 −
KEW 3121A KEW 3122A KEW 3123A
DC Test Voltage 2500V 5000 V 5000V 10000V
Measuring Ranges
0〜2000MΩ/
1000〜100000MΩ
（automatic change）
0〜5000 MΩ/
2000〜200000MΩ
(automatic change)
0〜5GΩ/2〜200GΩ
(automatic change)
0〜10GΩ/4〜400GΩ
(automatic change)
Accuracy Insulation
Resistance
±5% of reading
（100〜50000MΩ）
±10% of reading
or 0.5% of scale length
（ranges other than
listed above）
at 23℃±5℃
±5% of reading
（200〜100000MΩ）
±10% of reading
or 0.5% of scale length
（ranges other than
listed above）
at 23℃±5℃
±5% of reading
（0.2〜100GΩ）
±10% of reading
or 0.5% of scale length
（ranges other than
listed above）
at 23℃±5℃
±5% of reading
（0.4〜200GΩ）
±10% of reading
or 0.5% of scale length
（ranges other than
listed above）
at 23℃±5℃
±10% of reading
（100〜50000MΩ）
±20% of reading
or 1.0% of scale length
（ranges other than
listed above）
at −10℃〜＋40℃
±10% of reading
（200〜100000MΩ）
±20% of reading
or 1.0% of scale length
（ranges other than
listed above）
at −10℃〜＋40℃
±10% of reading
（0.2〜100GΩ）
±20% of reading
or 1.0% of scale length
（ranges other than
listed above）
at −10℃〜＋40℃
±10% of reading
（0.4〜200GΩ）
±20% of reading
or 1.0% of scale length
（ranges other than
listed above）
at −10℃〜＋40℃
Output
Voltage
2500V ±5%
（100〜50000MΩ）
5000V ±5%
（200〜100000MΩ）
5000V ±5%
（0.2~100GΩ）
10000V ±5%
（0.4~200GΩ）
Operating
Temperature & Humidity −10℃〜＋40℃at 85% max. relative humidity
Storage
Temperature & Humidity −20℃〜＋60℃at 90% max. relative humidity
Insulation Resistance 1000MΩmax./ 1000V between electrical circuit & housing case
Withstand Voltage 5000V AC for one minute between electrical circuit & housing case
Dimensions 200（L）×140（W）×80（D）mm
Weight Approx. 1kg（including batteries）
Power Source 8 pcs of R6P (AA) battery or equivalent
Accessories
Hard Carrying Case:M-9158 Test Leads
(Line Probe:M-7165A, Earth
Cord:M-7224A, Guard Cord:M-7225A)
Hard Carrying Case:M-9158 Batteries, Test Leads (Line
Probe:M-7165A, Earth Cord:M-7224A, Guard Cord:M-
7225A) Pickel type prod:M-8019
Optional accessories
Line cord with alligator clip：M-7168A
Optional adapter：M-8324
Pickel type prod:M-8019
Line cord with alligator clip：M-7168A
Optional adapter：M-8324
3. Specifications

−4 −
KEW 3121A KEW 3122A KEW 3123A
DC Test Voltage 2500V 5000 V 5000V 10000V
Measuring Ranges
0〜2000MΩ/
1000〜100000MΩ
（automatic change）
0〜5000 MΩ/
2000〜200000MΩ
(automatic change)
0〜5GΩ/2〜200GΩ
(automatic change)
0〜10GΩ/4〜400GΩ
(automatic change)
Accuracy Insulation
Resistance
±5% of reading
（100〜50000MΩ）
±10% of reading
or 0.5% of scale length
（ranges other than
listed above）
at 23℃±5℃
±5% of reading
（200〜100000MΩ）
±10% of reading
or 0.5% of scale length
（ranges other than
listed above）
at 23℃±5℃
±5% of reading
（0.2〜100GΩ）
±10% of reading
or 0.5% of scale length
（ranges other than
listed above）
at 23℃±5℃
±5% of reading
（0.4〜200GΩ）
±10% of reading
or 0.5% of scale length
（ranges other than
listed above）
at 23℃±5℃
±10% of reading
（100〜50000MΩ）
±20% of reading
or 1.0% of scale length
（ranges other than
listed above）
at −10℃〜＋40℃
±10% of reading
（200〜100000MΩ）
±20% of reading
or 1.0% of scale length
（ranges other than
listed above）
at −10℃〜＋40℃
±10% of reading
（0.2〜100GΩ）
±20% of reading
or 1.0% of scale length
（ranges other than
listed above）
at −10℃〜＋40℃
±10% of reading
（0.4〜200GΩ）
±20% of reading
or 1.0% of scale length
（ranges other than
listed above）
at −10℃〜＋40℃
Output
Voltage
2500V ±5%
（100〜50000MΩ）
5000V ±5%
（200〜100000MΩ）
5000V ±5%
（0.2~100GΩ）
10000V ±5%
（0.4~200GΩ）
Operating
Temperature & Humidity −10℃〜＋40℃at 85% max. relative humidity
Storage
Temperature & Humidity −20℃〜＋60℃at 90% max. relative humidity
Insulation Resistance 1000MΩmax./ 1000V between electrical circuit & housing case
Withstand Voltage 5000V AC for one minute between electrical circuit & housing case
Dimensions 200（L）×140（W）×80（D）mm
Weight Approx. 1kg（including batteries）
Power Source 8 pcs of R6P (AA) battery or equivalent
Accessories
Hard Carrying Case:M-9158 Test Leads
(Line Probe:M-7165A, Earth
Cord:M-7224A, Guard Cord:M-7225A)
Hard Carrying Case:M-9158 Batteries, Test Leads (Line
Probe:M-7165A, Earth Cord:M-7224A, Guard Cord:M-
7225A) Pickel type prod:M-8019
Optional accessories
Line cord with alligator clip：M-7168A
Optional adapter：M-8324
Pickel type prod:M-8019
Line cord with alligator clip：M-7168A
Optional adapter：M-8324

−5 −
④
⑤
③②①
④
⑦
⑥
⑧
⑪ ⑩ ⑨
4. Instrument Layout
①Line Terminal
②Guard Terminal
③Earth Terminal
④LED's for High & Low
Range Indication
⑤Press to Test Button
⑥Function Switch
⑦Meter Movement Zero
Adjust
⑧Battery Compartment
Cover
⑨Line Probe (Red)
⑩Earth Cord (Black)
⑪Guard Cord (Green) Fig.1

−6 −
CAUTION:
BE CAREFUL ABOUT HIGH VOLTAGE PRESENT ACROSS LINE
AND EARTH TERMINALS OF INSTRUMENT WHEN PRESS TO
TEST BUTTON IS OPERATED. MAKE SURE TO EARTH CIRCUIT
UNDER TEST. ALWAYS CONNECT EARTH TERMINAL OF
INSTRUMENT TO EARTH. THE BUZZER WILL KEEP SOUNDING
DURING INSULATION RESISTANCE MEASUREMENT.
5-1. Mechanical Zero Adjustment
With the function switch set at OFF position, adjust the meter
pointer to
∞ mark on the scale. Use a screwdriver to turn the
zero adjust screw located at the center of the front panel.
5-2. Battery Check
With the function switch set at BATT. CHECK position, operate the
press to test button. The batteries are good when the pointer stays
in BATT. GOOD area or to the right of this area. If not, replace them.
Note: Refrain from holding down or locking the press to
test button during this test as it will result in current
consumption larger than insulation resistance
measurement while the batteries are still new.
5. Operating Instructions

−7 −
5-3. Insulation Resistance Measurement
With the function switch set at OFF position, always connect the
circuit under test to earth. Attach the test lead to the earth terminal
of the instrument and connect to the earthed side of the circuit
under test. With the function switch set at 2500V and 5000V for
KEW 3121A and 3122A or 5000V or 10000V for KEW 3123A,
connect the black earth code to the earth terminal (EARTH) and
place the line probe in contact with the circuit under test and press
the Test button. When the green LED illuminates, read insulation
resistance on the outer scale (for high range). Use the inner scale
where the red LED illuminates. For insulation testing at 5000V
and 10000V, read the black and red scales respectively (for KEW
3123A). After a test, release the press to test button and wait for
several seconds without disconnecting the line probe from the
circuit tested. This is intended to discharge the charge stored in the
circuit tested.
5-4. Continuous Measurement
Make sure that the circuit under test is earthed and that the test
lead attached to the earth terminal of the instrument is connected
to the earthed side of the circuit under test. Push the press to test
button and turn clockwise to lock for continuous measurement.
When making this measurement, good care must be taken against
the high voltage continuously present across the line and earth
terminals of the instrument.
Note: Make certain that the circuit under test does not
include components which will be damaged by the
high voltage applied.

−8 −
5-5. Use of Guard Terminal
When measuring the insulation resistance of a cable, Ieakage
current flowing on the surface of cable jacket and the current
flowing inside the insulator are mixed and may cause error in
insulation resistance value. In order to prevent such error, wind a
conductive wire around the point where leakage current flows. Then
connect it to the Guard terminal as shown in below Fig.2. This is
to move out the surface leakage resistance of the cable insulation
to measure only the volume resistance of insulator. Make sure to
use the Guard cord supplied with this instrument to connect the
instrument to Guard terminal.
Connect the terminals with reference to the following figure of an
equivalent circuit.
* Wind a protective wire, any conductive bare wires are ok, around
the point where leakage currents flow. Then connect it to the
Guard terminal as follows.
* It is possible to move out the surface leakage resistance of the
insulation and measure only the volume resistance by using the
Guard terminal. This is helpful when performing tests in humid air.
Fig.2

−9 −
Remove the battery compartment cover by loosening the screw located
on the back of the housing case. Replace the whole battery pack. Alkaline
batteries are recommended where the instrument is used at a temperature
below the freezing point. The ordinary manganese batteries will deteriorate
below the freezing point.
6. Batttery Replacement
7-1. Metal part for Line Probe, and replacement
（1）Tip metal parts
MODEL8252: Standard Prod (straight type, with molded parts)
MODEL8254: Straight Type Prod
MODEL8019: Pickel Type Prod (accessory)
To be used to hook the instrument.
Note:Option KEW3121A, KEW3122A
（2）How to replace it
Turn the Line probe counterclockwise to remove the attached tip metal. Put the
tip metal you want to use to the hexagon socket and turn it to clockwise together
with the tip of probe，and tight up screws.
7. Accessories and options

−10 −
To shield or Earth
To recorder
Fig.3
7-2. How to use the adaptor for recorder
MODEL8324 is the adaptor for recorder for output current measurement. Connect
it as shown in the below Fig.3.
Output is DC10mV when current of 1μA is flowing．

−11 −
8. How to fix the Meter to the Hard case
Please follow the instructions below to fix MODEL9159 main unit to
MODEL9158 Hard case with Dual lock fastener.
1. Place a hard board beneath the Hard case.
The board should be located under the fastener attached to the Hard
case.
2. Put the unit in place, and then press down the sides of the unit so that
the mushroom-shaped stems on the fastener are engaged each other
with audible snap sound.
Duallockfastener
Ahardboardshouldbeplacedinthe
locationasindicatedbydottedlines.
Pressingdownthesidesofunit(as
indicatedbyarrowmarks)engages
thestemsonthefastener.

−12 −
9. Cleaning Meter Cover
This earth tester is managed by our company's quality standard and is
delivered in the best condition after passed the inspection. But in the dry
time of winter static electricity sometimes builds up on the meter cover due
to the characteristic of plastic.
When the pointer deflects by touching the surface of this tester or zero
adjustment can not be made, do not try to make measurement.
When static electricity builds up on the meter cover and affects the meter
reading, use a cloth dampened with off-the-shelf anti-statics agent or
detergent to wipe the meter cover surface.

DISTRIBUTOR
Kyoritsu reserves the rights to change specifications or designs
described in this manual without notice and without obligations.
7-11 92-1919C