Megger MOM2 Specifications
MOM2
Micro-ohmmeter
Handheld High Current Micro-ohmmeter
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Up to 240 A
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Bluetooth® headset for audible pass/fail
testing against adjustable limits
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Battery powered
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Handheld, lightweight – 2.2 lb (1 kg)
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Safe test – DualGround
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Auto range: 1 µΩ to 1000 mΩ
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Ultra capacitor technology (patent
™
pending)
MOM2
DESCRIPTION
The MOM2 Micro-ohmmeter is a lightweight, handheld
unit designed to deliver up to 240 Amps and measure the
resistance of circuit breaker contacts, bus-bar joints, and
other high-current links. This product is designed with
safety, ease of use and versatility in mind.
The MOM2 can be used anywhere to measure a low
resistance value with high accuracy. With the MOM2,
it is possible to make measurements according to the
DualGround™ method. This means that the test object will
be grounded on both sides throughout the test giving a
safer, faster and easier workflow.
Its ruggedness and light weight make the MOM2 very
suitable for field work, such as in substations. The unit
comes with a strong rubber holster accessory which makes it
extra durable. The MOM2 is capable of testing for a full day
without recharge. It can store 190 test values and transfer
test data to a PC via Bluetooth.
The Bluetooth feature can also be used in conjunction with
the wireless headset to provide an audible pass/fail signal
against user-adjustable limits as tests are performed.
High Current Generation Using Ultra Capacitor
The MOM2 uses an ultra capacitor to generate the highoutput current. Ultra capacitors are able to store huge
amounts of energy compared to conventional capacitors. In
addition, they can deliver very high currents during discharge
as a result of their very low internal resistance.
While testing, the capacitor is discharged through the
test object. The voltage drop across and the current flow
through the test object are continuously and synchronously
sampled. The resistances calculated from the individual
samples are then averaged to obtain the final value.
APPLICATIONS
The MOM2 test system is designed to serve a number of
applications. The most common are contact resistance
measurements of low-, medium- and high-voltage breakers
and also at bus-bar joints, and other high current links.
If the contact resistance is too high, this will lead to power
loss and temperature rise, which often leads to serious
trouble. To avoid such problems, it is necessary to check the
resistance at regular intervals.
The following table demonstrates how important low
resistance is at high currents:
Current Contact resistance Power loss
10 kA 1 mΩ 100 kW
10 kA 0.1 m Ω 10 kW
1 kA 1 mΩ 1 kW
1 kA 0.1 m Ω 100 W
At 10 kA a contact with the resistance 0.1 mΩ gives a
power loss of 10 kW. This power loss in one single point
will definitely confer a temperature rise, which may result in
overheating and possibly premature failure.
MOM2
Handheld High Current Micro-ohmmeter
INSTRUMENT FRONT VIEW
1. Current output terminal (-)
2. Current output terminal (+)
3. Display
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The display offers a combination of analog arc and a
dual digital readout:
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Analog arc:
Indicates level of the capacitor charge.
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Dual digital display:
Large main digital readout for good visibility of all
main measurement results
Second digital display for additional data.
4. Ground (earth) terminal
5. Keys for navigation and to make settings in the display
6. TEST-button
7. Stand-by/Wake up (Press shortly to toggle)
Clear log (Press and hold for 5 seconds)
8. Function selector
OFF
I > I min
I = I max
0.1 s
0.6 s
3 s
0.1 s
0.6 s
3 s
Measurement time with
minimum current guarantee
Measurement time with max. charge
Bluetooth “pair units”
CLK
Set date and time
Set volume for the internal
loudspeaker
SET
Discharge the MOM2 internal
capacitor
PC COM
USER
I min
LOG
P/F
1
2
3
Minimum current guarantee setting
Data log settings
Pass/Fail settings
PC communication
(dump data to PC)
Stored settings. Set from PC,
MOM2Win
9. Connector for the voltage (–) sense lead
10. Connector for the voltage sense (+) lead and the trig
function
11. Connector for the battery charger
12. Battery charger indicator
9 10
1 2
3
4
5
6
7
8
11
12
4 wire Kelvin test
The Kelvin probes (included in BD-59090) are used for a 4-wire Kelvin
test. This is a way of measuring continuity resistances ensuring all
contact and lead resistances are compensated for, allowing a much
greater accuracy in measurements. Each Kelvin probe assembly has two
probe tips: one tip is for the current generated; the other will measure
the very small voltage present.
The Kelvin clamps (included in BD-59092) use the same principle.
The "double" probe tip showing the springy center tip
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