Adwel Industiries Ltd, of Chiswick, London, offer an early-warning system for protecting polyphase electric motors against damage. Known as Motor Guard, the system is easily fitted and will protect motors of any size against such faults as single-phasing; unequal voltages, currents, and capacitive compensation; inter-turn short circuits; negative phase sequencing; faulty bearings, and major rotor faults. Optional extra equipment includes devices giving sensitive protection against overloading and protection for loss of phase before the motor is started, a trip indicator to discriminate between overloading and supply asymmetry faults, and a variable time-delay. The article briefly describes the operating principles of the system, and mentions its many features. Its main components are a current transformer, a solid-state control unit, and a sensor coil for fitting to the motor. A timer protects against spurious operation by transient conditions; the system can be arranged to operate an alarm when the supply fails, without tripping the motor. Under fault conditions such as gradual bearing failure, the system's meter reading would slowly fall towards zero, and the motor could then be taken off-line before a complete breakdown occurred; this facility could be utilized in existing planned maintenance schedules.

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  • Corporate Authors:

    Engineering, Chemical and Marine Press, Limited

    33-39 Bowling Green Lane
    London EC1P 1AH,   England 
  • Publication Date: 1977-3

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Filing Info

  • Accession Number: 00163441
  • Record Type: Publication
  • Source Agency: British Ship Research Association
  • Files: TRIS
  • Created Date: Oct 29 1977 12:00AM