• Performance and accuracy testing of single- and three-phase grounded or non-grounded instrument voltage transformers of 0.2 accuracy class (or less accurate) with 50-Hz frequency rated from 6 to 10 kV (to 35 kV). The Test Set is suitable for primary (post-manufacture) or regular testing of transformers in load points defined by the standard or under an actual load on the secondary side of the VT under test
  • Check of phase rotation in 3-phase circuits
  • Measurement of load power

The test set can be used independently or as part of a mobile test lab.

Field of application

Accounting (billing) systems in electrical energy sector.


  • Components are compact and light-weight (can be carried from the vehicle to the location of transformers under test by two persons)
  • Suitable for testing either single-phase or 3-phase VTs; Phase-to-phase voltages of 3-phase VTs can be tested using differential connection scheme which includes two reference units (CHVTs)
  • Control of test signal quality - using the comparator, it is possible to view the wave shape, THD and harmonics of the applied test signal

A mobile Marstest-VT-3 test set can contain the following components:

  • Console unit
  • Voltage regulating transformer
  • Source of test signal - generating voltage transformers (3 units)
  • Source of reference voltage - Capacitive High-Voltage Transducer (CHVT) + Instrument amplifier of voltage (UIN): CHVT-10; CHVT-35
  • Comparator – multifunctional reference instrument Energomonitor 3.3T1 (complete with VTCS switch module)
  • Burden boxes MP 3025 (4 units)
  • Laptop, software

Marstest-VT-3 Transformer Test System consists of individual units connected to each other with power, measurement, control and high-voltage cables.

High-Voltage Three-Phase Test Set for accuracy testing/ calibration of Voltage Transformers with the primary nominal voltage from 6 to 35 kV in the operating range 40% to 120%.
Accuracy class:   0.1; 0.05
Purpose: Laboratory / On-site accuracy testing and calibration of single- and three-phase instrument voltage transformers (customer-selected ranges up to 35 kV). Accuracy class of transformers under test: 0.2 (0.5), or less accurate.
Scope of supply

1. Comparator: 
Option 1: Energomonitor 3.3T1 (for testing VTs of 0.5% accuracy) or 
Option 2: Energomonitor 3.1KM (for testing VTs of 0.2% accuracy)

2. Reference Device: Reference Capacitive High-Voltage Transducer (CHVT series)

- CHVT-10-2 (3…10 kV range) or 
- CHVT-35-2 (11…35 kV range) complete with UIN-D amplifiers

3. High Voltage Source
      Test Transformer Set:
  • Option 1: Set of dry-type VTs (3 pcs for three-phase testing), or 
    Option 2: Set of IOG-type (SF6) VTs (3 pcs; supplied on request)
  • 3-phase Variable-ratio transformer
  • 3-phase Console Unit (CU-3-35)
4. Burden Boxes  100/√3 V, 80 VA; 100 V, 80 VA (3 pcs) – for 10kV set;
100 V, 200 VA (3 pcs) – for 35kV set
5. Set of cables (power, control, measurement, grounding, corona-free etc.)
6. Personal Computer (Laptop), printer, software

* The customer can opt for the Reference Capacitive HV Transducer CHVT with the desired internal voltage measurement ranges (subject to special order).