US 4,360,847 AGranted

Diode assisted relay contactor

AssigneeGeneral Electric Company

InventorsMilton D. Bloomer, Joseph L. Ciccone, John D. Harnden, Jr., William P. Kornrumpf, Donald P. Shattuck

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Abstract

A switching circuit having hybrid contactors connects the three output lines of a 3 phase AC power source to three input lines of a load, such as a motor and the like. A single pair of relay contacts is used to directly connect one output line of the AC power source to one input line of the load, whereas each of the other two phases of the AC power source are supplied to the load by one of a pair of pilot relay contacts in series with a diode-shunted one of a pair of master relay contacts. Only two extra pilot relays are used to provide a reversing function. The switching circuit further includes a zero-crossing detector, a phase-sequence detector, a control circuit including four flip-flops arranged in a tumble-down chain and a single distribution circuit having a data select circuit. The control circuit causes the making and breaking of the contacts at particular times, and in a sequence, such that arcing is prevented.

Claims25

Dependent claims

A method of switchably connecting and disconnecting first, second and third output lines of a threephase AC power source to first, second and third input lines of a load, the steps comprising:

I. turning on a flow of power from said AC power source to said load by:
(a) making an ohmically-isolated pair of first-line relay contacts, to establish a direct two-way current conduction path between said first output line of said AC power source and said first input line of said load;
(b) making an ohmically-isolated pair of second-line pilot relay contacts after, or at the same time as, step I(a), to establish a one-way current conduction path through a second-line diode between said second output line of said AC power source and said second input line of said load, the second-line pilot relay contacts making only when the second-line diode is reversed-biased by said AC power source;
(c) making a pair of second-line master relay contacts shunted by, and associated with, said second-line diode after step i(b) and only when the second-line diode is forward biased by said AC power source, to establish a two-way current conduction path between said second output line of said AC power source and said second input line of said load;
(d) making an ohmically-isolated pair of third-line pilot relay contacts after, or at the same time as, step I(a), to establish a one-way current conduction path through a third-line diode between said third output line of said AC power source and said third input line of said load, the third-line pilot relay contacts making only when the third-line diode is reverse biased by the AC power source;
and
(e) making a pair of third-line master relay contacts shunted by, and associated with, said third-line diode after step I(d) and only when the third-line diode is forward biased by said AC power source, to establish a two-way current conduction path between said third output line of said AC power source and said third input line of said load;
and
II. turning off the flow of power from said AC power source to said load by:
(a) breaking one of said pairs of second-line and third-line master relay contacts when the associated shunting diode is forward biased by the AC power source;
(b) breaking the pair of pilot relay contacts associated with the master relay contacts of step II(a) after step II(a) and only when the associated line diode is reverse biased;
(c) breaking the other one of said pairs of second-line and third-line master relay contacts only when the associated line diode is forward biased by the AC power source;
source;
(d) breaking the other one of said pairs of pilot relay contacts after step II(c) and only when the associated line diode is reverse biased;
(e) breaking the pair of first-line relay contacts after, or at the same time as, the last occuring of steps II(b) and II(d).

12 more elements

A switching circuit system for controlling the flow of power from first, second, and third output lines of a three-phase AC power source to first, second, and third input lines of a load, comprising:

an ohmically-isolated pair of first-line relay contacts for directly, switchably connecting the first output line of the AC power source to the first input line of the load;
a pair of second-line master relay contacts shunted by a second-line diode and attached in series with an ohmically-isolated pair of second-line pilot relay contacts for switchably connecting the second output line of the AC power source to the second input line of the load;
a pair of third-line master relay contacts shunted by a third-line diode and attached in series with an ohmically-isolated pair of third line pilot relay contacts for connecting the third output line of the AC power source to the third input line of a load;
a detecting circuit for detecting a first relative waveform from at least two of said output lines of said AC power source and generating a first indicating signal based on said first relative waveform;
an input signal circuit for generating at least a START signal;
and
a control circuit for controlling the state of all of said pairs of relay contacts and which receives said first indicating signal and said start signal, said control circuit including means responding to the START signal for:
making said first-line relay contacts before, or at the same time as, either one of said pair of second-line pilot relay contacts and said pair of third-line pilot relay contacts makes;
making said pair of second-line pilot relay contacts only when the second-line diode is reverse biased by the AC power source;
making said pair of second-line master relay contacts after the making of the second-line pilot relay contacts and only when the second-line diode is forward biased by the AC power source;
and
making said pair of third-line pilot relay contacts only when the third-line diode is reverse biased by the AC power source;
and making said pair of third-line master relay contacts after the making of the third-line pilot relay contacts and only when the third-line diode is forward biased by the AC power source.

10 more elements

Dependencies are inferred from the claim text.

Facts

Application: 06/222,410Filed 5 Jan 1981
Granted: 23 Nov 1982
Term ends: Not estimatedThe source records don’t support an estimate.

Classification7 codes

H01H 9/56
Circuit arrangements not adapted to a particular application of the switching device and for which no provision exists elsewhere: for ensuring…
G01R 19/175
Arrangements for measuring currents or voltages or for indicating presence or sign thereof: indicating the instants of passage of current or…
H01H 9/541
Circuit arrangements not adapted to a particular application of the switching device and for which no provision exists elsewhere: contacts shunted…
H01H 9/563
For ensuring operation of the switch at a predetermined point in the AC cycle: for multipolar switches, e.g. different timing for different…