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100ADM-F Filter Unit

4.5 (2 reviews)

  • Forces test current to a sinusoid
  • Improves timing accuracy when testing electro-mechanical relays
  • 0.25A – 100A ranges
  • High overload capability
  • 50/60Hz operating frequency
  • High efficiency


The 100ADM-F Filter Unit reduces the level of current harmonics when testing electro-mechanical protection relays. It is designed for use with our range of secondary injection test sets.

All electro-mechanical protection relays have iron cores that saturate and distort the test current under high overload test conditions. The distortion causes significant errors in the measured trip time of these relays during testing. Distortion of the waveform can be a particular problem with disc induction type over-current and sensitive earth fault relays.

For example, testing a CDG11 disc induction over-current relay without a filter causes significant timing errors. The results bellow show the errors for a 1.3s 1A CDG11 over-current relay on its 0.5A plug setting, tested at 5A.

100ADM-F Table

The 100ADM-F Filter Unit has nine current ranges covering 0.25A to 100A and is supplied in an insulated case, complete with protective cover and carrying strap.

RangeContinuous rating5 min on/ 15 min off

The unit may be used at either 50Hz or 60Hz, selectable by a switch on the front panel. The lower ranges (0.25A-50A) are selected by a switch, and the highest current range is selected by a terminal. A current monitoring output is provided on all the filter units that provides an output of 0-100mA corresponding to the rated current for the range. Table below gives the impedance in ohms of the filter unit against frequency on each range.

RangeImpedance (Ω)

Our partners, such as AcutestAlpha ElectronicsCuthbertson LairdNorwich Instrument Services, and PASS Ltd , offer the 100ADM-F in the United Kingdom. Additionally, if you are located outside Great Britain, you can conveniently order the product through our worldwide distribution network.

100ADM-F Datasheet


Additional information

Net Weight

15.6 kg

Net Dimensions

340 × 230 × 330 mm

Supplied Accessories

Calibration certificate

2 reviews for 100ADM-F Filter Unit

  1. Olivia Smith

    We have been using one for years along with other T&R Test Equipment products. 5 starts for reliability and functionality. Design is old, could be improved, 2.5 stars on that aspect. I’ll round it up to 4 stars because my colleagues find it very useful and T&R is always happy to provide support.

  2. André dos Santos

    Just got one back after sending it for case replacement and recalibration. Still works like a charm after 10 years in the field.

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