100 Amp Precision AC/DC Transconductance Amplifier

Model 2555A

2555A 100 Amp Precision AC/DC Transconductance Amplifier Front View
2555A 100 Amp Precision AC/DC Transconductance Amplifier Side View
100 Amp Precision AC/DC Transconductance Amplifier
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  • Up to 20 Amps/phase direct (self contained shunt 0.1%)
  • Precision AC/DC Transconductance Amplifier
  • Programmable AC~DC 100Amp Current Calibrator/Current Source
  • Calibration Traceable to NIST
  • Maximum Output Current: 100A DC or RMS AC
  • Highly Accurate
  • Ultra-low Noise
  • Ultra-Stable
  • Excellent Response time
  • High CMR
  • Load Regulation: Output current Δ < ± .002%
  • Dynamic Range: 0 to 100% of range up to maximum rated output (100A max.)


  • R3 – 19″ Rack Adaptor Kit
  • HC – 100A Cable Set (Spade Lugs)
  • C-1000 – 10 Turn Coil Loop (C.T. Type)
  • HMF – 100A Cable Set (Jaws Terminated)
  • BBL – Banana-to-Banana Cable Set

World’s Leading Precision 100-Amp AC/DC Current Standard.

For 30 years Valhalla Scientific’s design has proven rock-solid reliability in metrology labs worldwide.

Calibration powerhouse with wide-ranging applications

Capable of delivering from 1mA to 100 amps DC or RMS AC of precise constant current, the 2555A is ideal for direct calibration of ammeters, wattmeters, DMM’s, shunts, current transformers and Hall effect devices. The superb stability of Valhalla’s patented transconductance amplifier technology allows the 2555A to be used for transfer measurements on .001 ohm primary resistance standards. Applications for the 2555A outside of the field of metrology include component testing on fuses, circuit breakers, relays and high current connectors.

Constant current

The 2555A supplies four volts of compliance in order to drive heavy burden loads and still delivers constant current. The output compliance is continually monitored by the unit’s internal voltmeter. Compliance status is displayed at all times on the 2555A’s compliance indicators.

To ensure that the compliance voltage is available to drive the load (and not the leads), Valhalla offers two heavy duty six foot 100 amp cable sets. The “HMF” set is terminated in 2″ opening, 500 amp rated, injection molded clamps, while the “HC” version is terminated in no. 4 copper ring lugs.


Simulate 1000 Amps

Valhalla offers the option “C1000” along with the Valhalla 2555A, to make the calibration of clamp-on ammeters, current transformers, and a variety of current sensor (magnetic field based) devices a simple task. The basic principle envolves the 2555A driving 100 amps per turn into a 10 turn coil. The Valhalla 2555A Current Calibrator can easily drive the ten turn option “C1000” and simulate 1000 amps. By placing the clamp-on ammeter around and thru the windings of the “C1000” the clamp-on meter under test can be verified for accuracy, and frequency response.

The Valhalla 2555A is the “workhorse” in the metrology lab for the calibration of current shunts, ammeters, clamp-on meters, current transformers, and even low value resistance standards. The metrology lab isn’t the only place a Valhalla 2555A comes in useful. Production departments and Quality Control test areas using the Valhalla 2555A can also benefit. Many companies improve their product reliability by using the 2555A for the screening of fuses, relays, circuit breakers, and a multitude of current sensor incorporated devices.