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KVTS Voltage Transformer Test System


The Knopp Voltage Transformer Test System (KVTS) is designed to measure the accuracy of instrument transformers having 120 volt secondaries and up to 36,000 volt primaries. The system includes a control console which contains the control circuitry, ANSI standard burdens, and the Knopp Automatic Transformer Comparator. The Knopp precision and loading transformer sets (Types 2J4-4 and 2J6) are separate units and are connected to the KVTS console via a special cable (included).


A. General

  1. The test system shall consist of a control console and a separate precision/loading transformer set.
  2. The test system shall be able to check the accuracy of instrument transformers having primary ranges from 120 to 14,400 volts.
  3. The test system shall include a built-in, microprocessor-controlled, automatic, auto-ranging comparator.
  4. The test system shall incorporate protective circuitry to ensure the safety of the operator, the test system, and the transformer-under-test.
  5. The accuracy or calibration of the precision transformer must be traceable to the National Institute of Standards and Technology.
  6. The test system shall be suitable for 60 Hz. operation.

B. Test Ranges

  1. The following primary ranges shall be provided: 120; 240; 480; 600; 2,400; 4,200; 4,800; 7,200; 8,400; 12,000; and 14,400 volts.
  2. The secondary voltage shall be 120 volts.
  3. Transformers shall be able to be tested from 50% to 120% of the selected voltage.

C. Test Burdens

  1. The following ANSI burdens shall be switch selectable: W, X, M, Y, Z, and ZZ
  2. These burdens shall be very stable and highly accurate (the resistive and inductive component values shall be accurate to within 1%).
  3. Provisions shall be made for connection of an external burden.

D. Comparator

  1. The comparator shall be dedicated to the test system. It shall only be capable of testing voltage transformers.
  2. The comparator shall be automatic and autoranging to provide minimum measurement time. Measurements shall be completed within 5 seconds of adjusting the test voltage.
  3. The comparator shall digitally display test voltage and test results. Test results shall consist of ratio error (in % or RCF) and phase error (in minutes or milliradians).
  4. The comparator shall calculate and digitally display the best accuracy class for which the transformer-under-test qualifies.
  5. The comparator shall include protective circuitry which senses error conditions such as wrong ratio or wrong polarity and then automatically removes power from the test system loading circuitry.
  6. The comparator shall offer printer or RS-232 test result output options.

E. System Accuracy

  1. The combined error of the precision voltage transformer and the transformer comparator shall be no greater than 0.025% on ratio and 2 minutes on phase angle at 100% full load voltage.

F. Self Check

  1. The calibration of the precision transformer shall be able to be periodically checked by the One-to-One method, whereby the ratio and phase angle performance can be quickly and accurately checked without the use of an external reference standard.

G. Input Power Requirements

  1. The test system shall operate off of 120 or 240 volt, single-phase service at a nominal 10 amperes.

H. Weight and Dimensions

  1. The approximate weight of the test system control console shall be 350 lbs. (159 kg).
  2. The test system control console shall measure 61.5 in. (156.5 cm) High, 24 in. (61 cm) Wide, and 37 in. (94 cm) Deep.
  3. The approximate weight of the test system precision/loading transformer set shall be 370 lbs. (168 kg).
  4. The test system precision/loading transformer set shall measure approximately 40 in. (101.6 cm) High, 20 in. (50.8 cm) Wide, and 15 in. (38.1 cm) Deep.

I. Instruction Manual

  1. An instruction manual including schematic diagrams shall be furnished with the test system.

J. Options

  1. A printer for printing test results shall be able to be purchased separately.

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