MOM2 Handheld High Current Micro-ohmmeter
The Megger BD-59093 MOM2 Microhmmeter uses an ultra capacitor to generate the high output current. The ultra capacitor is able to store a huge amount of energy compared to conventional capacitors and can deliver very high current during the discharge thanks to its very low internal resistance.
The Megger BD59093 MOM2 Microhmmeter can be used anywhere to measure a low resistance value with high accuracy. With 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. This gives a personal safe, quick and easy measurement.
The ruggedness and lightweight makes Megger BD-59093 a handheld instrument very suitable for field work, such as in substations. The unit comes with a strong rubber holster accessory which makes it extra durable. MOM2 is dimensioned to make a full day’s work of testing without recharge. It can store 190 test values and transfer test data to a PC via Bluetooth.
Low weight, ease of use and versatility has been key issues during product development. New patent pending technology has made MOM2 small and light, it weighs about 1 kg. Despite the small size and light weight the instrument can deliver a maximum current of about 220 A short duration and up to 100 A for three seconds.
High current Generation Using Ultra capacitor
The MOM2 uses an ultra capacitor to generate the high-output 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.
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 mΩ||10 kW|
|1 kA||1 mΩ||1 kW|
|1 kA||0.1 mΩ||100 W|
At 10 kA a contact with the resistance 0.1 mO 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.
BOTH SIDES GROUNDED
Within electrical power utilities, switchgear owners and service companies, there is an increased emphasis on efficiency of operations, maintenance and service levels. There is an increased emphasis on health, safety, and environmental compliance. Experience has also shown demands for shorter time periods for testing, while the switchgear is less and less available to be taken out of service.
Many utilities require safety grounds to remain in place during station outages, therefore, the MOM2 was designed with this field safety constraint in mind. DualGround means that the test object will be grounded on both sides throughout the test giving a safer, faster and easier workflow. Minimum time shall be spent in the substation and focus shall be on the test rather than the equipment.
|Specifications are valid at fully charged batteries and an ambient temperature of +25°C, (77°F). Specifications are subject to change without notice.|
|Application field||For use in high-voltage substations and industrial environments.|
|Temperature||Operation||-20ºC to +50°C (-4°F to +122°F) *|
|Storage||-40ºC to +70ºC (-40°F to +158°F)|
|Relative humidity %RH||5%-95%, non condensing|
|* Battery operation temperature 0ºC to +50° (32°F to +122°F)|
Battery charging temperature +10ºC to +40° (50°F to +104°F)
|Battery power||Five AA (HR6) 2700 mAh NiMH cells|
|Recharge time||< 12 h|
|Typical recharge time at 25°C||3 h|
|Battery charger||Mains voltage||100 – 250 V AC, 50 / 60 Hz|
|Mains voltage||100 – 250 V AC, 50 / 60 Hz|
|Power consumption||60 W|
|Protection||Against wrong battery type, low/high temperature|
|Real time clock battery life||=10 years|
|Audible feedback||Different buzzer sounds|
(excl. binding posts)
|217 H x 92 B x 72 D mm|
8.5 H x 3.6 B x 2.8 D in.
|Weight||1.0 kg (2.2 lbs) instrument only|
5.0 kg (11 lbs) with accessories and carrying case
|Minimum current guarantee||Selectable 50 A / 100 A Valid at resistance ≤2mΩ|
|Pass / Fail||Settable from 1 µΩ to 1999 mΩ|
|Number of measurements on fully charged batteries||typ. 2200 at I min = 50 A and 0.1 s|
typ. 800 at I min = 100 A and 0.1 s
|Range||0 – 1000 mΩ|
|Resolution||0 – 999 µΩ||1 µΩ|
|1.0 – 9.99 mΩ||0.01 mΩ|
|10.0 – 99.9 mΩ||0.1 mΩ|
|100 – 1000 mΩ||1 mΩ|
|Inaccuracy||0 – 1999 µΩ||±1 % of reading ±1 digit|
|2 – 1000 mΩ||±2 % of reading ±1 digit|
|Outputs + / –|
|Range||> 100 A DC (R < 2 mΩ)|
|Output voltage (max)||2.5 V DC|
|Generation duration||Selectable: 0.1 s, 0.6 s, 3 s|
|SENSE + / –||Connector||4 mm banana jack|
|Voltage||±3 V DC|
|Trigger input||Threshold 8 V DC|
|DC IN||12 – 24 V DC, 2 A max|
|Logger, Data||Label. Timestamp, I max, I min, I Limit, Resistance, Meas.time, P/F limit|
|Labeling schemes||Circuit breaker oriented or running numbers|