function: 35 tyco electronics / www.tycoelectronics.com / factory direct technical support: 800-253-4560, ext. 2023 (u.s., canada, mexico) or 805-220-2020, ext. 2023 (international) ansi/ieee c37.90-1978 current differential relays are used for the protec- tion of transformers, motors and generators, by comparing the magnitude of the current entering and leaving the protected circuit. on a given phase winding, any difference between the two currents will indicate an internal fault; the relay will sense the vectorial difference between the two currents of the protected section and will initiate a quick disconnec- tion of the unit, to prevent disastrous consequences. the relay may also be used to protect internal faults on transformers, such as: ground faults, shorted winding, leakage between primary and secondary, etc. it will sense and compare primary vs. secondary currents, once the turns ratio has been taken into consideration. operation: with control voltage applied, the output contacts (shown in the de-energized position) will remain de- energized as long as the difference between the two input currents remains below the preset trip value. the contact will transfer to the engerized position when the current difference exceeds the trip value. current differential relay product specifications sample part no. WCD-230AC-1-A type: wcd - close differential control voltage vac & vdc 120ac 208ac 230ac 380ac 416ac 460ac 525ac 575ac trip adjustment range .5 = 0.1 amp to 0.5 amp 1 = 0.2 amp to 1.0 amp 2 = 0.4 amp to 2.0 amp options a = two normally open contacts b = two normally closed contacts h = contacts rated 3 amp at 125 vdc p = transient protection is provided in compliance with ansi/ieee c37.90-1978 consult factory for additional models. part number selection notes: 1. remove black screws for access to the trip adjustments. 2. clockwise rotation of the adjustment potentiometer will raise the current differential trip point. 3. the output contacts are shown de-energized. part number selection part number line current ..................................... control voltage ................................ differential trip point ....................... operating temperature .................... burden .............................................. output contacts ............................... contact ratings ................................ wcd series single phase, ac current, 50-400 hz direct or from ct 5 amp continuously 20 amp 30 seconds 200 amp, 0.10 seconds see part number selection screwdriver adjustable. see part number selection -40 o c to +75 o c current input: 2.5 va max. control voltage dc: 2 w max. ac: 2 va max. one set, n.o., one set n..c. 5 amp resistive at 120 vac or 28 vdc 25dc 48dc 125dc 87 .172 dia. 4 mtg. holes 3 3 7 / 8 4 5 / 8 4 4 1 / 2 4 7 / 8 terminal strips #6 - 32 screws wilmar ? protective relays C wcd series note: dimensions in inches. multiply values by 25.4 for dimensions in mm.
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