Electricity: motive power systems – Automatic and/or with time-delay means – Plural – diverse conditions or with time-delay means
Patent
1987-03-31
1988-05-10
Ro, Bentsu
Electricity: motive power systems
Automatic and/or with time-delay means
Plural, diverse conditions or with time-delay means
318430, 318442, 318445, H02P 128
Patent
active
047438169
ABSTRACT:
Motor protection relay is taught in which a microprocessor is utilized in conjunction with a reduced voltage motor starter and the electrical motor system which it operates upon to cause the motor to start in stages. The microprocessor-based system infers a start by the presence of a minimal amount of electrical current flowing in the three-phase system which supplies power to the motor starter and thence to the motor. After the start has been inferred, the microprocessor controlled protection device will issue a transition command for the second stage of the start operation where higher voltage is placed across the motor terminals when the in-rush current has fallen to a predetermined programmable value which approximates full load current, for example. An "incomplete sequence" feedback line is provided which is supplied from the auxiliary contacts of the low voltage starter to the microprocessor.
REFERENCES:
patent: 4288828 (1981-09-01), Kuntner et al.
patent: 4320328 (1982-03-01), Rudolph, Jr.
patent: 4476423 (1984-10-01), Mallick, Jr. et al.
Moran M. J.
Ro Bentsu
Westinghouse Electric Corp.
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