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Type FS-9 Closed-Link Test System

Functional Description and Specifications


The Type FS-9 Closed-Link Test System, in combination with a watthour reference standard, is used for testing watthour meters in the field. The primary purpose of the FS-9 is to test Class 100 and 200, 240 volt, single-phase, three-wire watthour meters (ANSI Forms 2 and 4) with the links closed. The FS-9 can also be used to test Forms 1 and 3 and some polyphase meters. Knopp precision transformers provide two isolated and identical currents necessary for closed-link, three-wire testing. These transformers also supply the reference standard with a constant 5 amperes regardless of the selected current.

All tests are performed at unity power factor. An "off" position is provided on the current select switch so that a creep test (voltage only) can be performed. In addition to fuse protection, two neon lamps are provided to indicate improper connection to the meter-under test.

The FS-9 is mounted in a fiber carrying case which also includes space for the reference standard and for the FS-9 lead set. A removable tray allows storage for miscellaneous user-supplied tools.



  • 22 in. (55.9 cm) Wide, 13.5 in. (34.3 cm) High, 11.5 in. (29.2 cm) Deep.


  • Approximately 47.2 lbs. (21.4 kg) with standard.

  • Approximately 41.7 lbs. (18.9 kg) without standard.

Input Voltage

  • 120 or 208 volts.

Test Current

  • Full Load:  5, 15, and 30 amperes.

  • Light Load:  0.5, 1.5, and 3 amperes.

Meter Types Tested

  • 120 volt, 2 wire

  • 240 volt, 2 wire

  • 120 volt, 3 wire and

  • 240 volt, 3 wire


  • None added to the source by the FS-9.

Duty Cycle

  • Continuous under all normal operating conditions.


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