Automatic transfer control device

• US 4,384,213 A
• Filed: 07/24/1978
• Issued: 05/17/1983
• Est. Priority Date: 07/19/1976
• Status: Expired due to Term

• Current Assignee: Westinghouse Electric Company LLC (Brookfield Asset Management Incorporated)
• Original Assignee: Westinghouse Electric Company LLC (Brookfield Asset Management Incorporated)
• Inventors: Bogel, George F.
• Primary Examiner(s): SCHREYER, STAFFORD
• Application Number:
  US05/927,307
• Time in Patent Office: 1,758 Days
• Field of Search: 307/43, 307/23, 307/29, 307/64, 307/68, 307/70, 307/80, 307/85, 307/86, 307/87, 364/480, 364/481, 364/492, 364/494
• US Class Current: 307/64
• CPC Class Codes: H02J 3/42 with automatic parallel connection when synchronisation is achieved
• CPC Class Codes: H02J 9/00 Circuit arrangements for emergency or stand-by power supply, e.g. for emergency lighting

Abstract

An automatic control transfer device for selectively energizing an electrical distribution system from a pair of electrical power sources. The device includes means for sensing electrical conditions on both of the sources and programmable electronic digital logic to selectively energize associated circuit interrupters for switching a distribution system between the two sources. A plurality of time delay functions are provided utilizing a separate oscillator for each function, each oscillator providing input to a common digital counter. The device senses the status of associated circuit interrupters to provide interlocking and lockout functions as well as proper switching commands for either two- or three-circuit interrupter systems. Means are also provided for testing the entire device without initiating an actual source transfer.

Claims

1. Automatic transfer control apparatus for selectively energizing an electrical distribution network from a plurality of electrical power sources, comprising:

a plurality of source sensing means for sensing electrical parameters on said electrical power sources;

means for generating output control signals for associated circuit interrupters to selectively connect and disconnect said electrical power sources to said distribution network;

means connected to said source sensing means for generating activating signals to said output control signal generating means in response to electrical parameters on said electrical power sources;

means for indicating the activating signals being supplied to said output control signal generating means;

means connected to said source sensing means for simulating abnormal electrical parameters on at least one of said sources; and

means for inhibiting the generation of said output control signals when said simulation means are activated.

2. Apparatus as recited in claim 1 comprising means for placing said apparatus in a "live test" mode, wherein said inhibiting means are activated and said indicating means are operated in a pulsing manner whenever activating signals are supplied to said signal generating means, whereby operating personnel are informed by the pulsing operation of said indicating means that said apparatus is in a "live test"mode and associated circuit breakers will not be operated.

3. Automatic transfer control apparatus for selectively energizing an electrical distribution network from a pair of electrical power sources through associated circuit interrupters, comprising:

first source sensing means for sensing electrical parameters on one of said electrical power sources;

second source sensing means for sensing electrical parameters on the other of said electrical power sources;

a plurality of means for generating output control signals for associated circuit interrupters to selectively connect and disconnect said electrical power sources to said distribution network;

electronic digital logic means for activating said signal generating means in response to changes in electrical parameters detected by said sensing means; and

means for programming said logic means to automatically command said signal generating means to selectively produce any of a predetermined set of output signal combinations in response to a predetermined set of electrical parameters from said electrical power sources;

said programming means comprising means cooperating with said electronic digital logic means for selectively placing said apparatus in a "Keep Last Source" mode, wherein said signal generating means are prevented from generating a trip signal to an associated circuit breaker connected to one of said sources, said prevention function being performed under the following conditions;

(1) said apparatus has previously initiated a transfer operation in which said electrical distribution system has been connected to said one of said sources, and

(2) said one of said sources subsequently fails, and

(3) the other of said sources remains failed.

4. Automatic transfer control apparatus for selectively energizing an electrical distribution network from a pair of electrical power sources through associated circuit interrupters, comprising:

first source sensing means for sensing electrical parameters on one of said electrical power sources;

second sources sensing means for sensing electrical parameters on the other of said electrical power sources;

a plurality of means for generating output control signals for associated circuit interrupters to selectively connect and disconnect said electrical power sources to said distribution network;

electronic digital logic means for activating said signal generating means in response to changes in electrical parameters detected by said sensing means;

means for programming said logic means to automatically command said signal generating means to selectively produce any of a predetermined set of output signal combinations in response to a predetermined set of electrical parameters from said electrical power sources;

means for indicating the activating signals being supplied from said electronic digital logic means to said output signal generating means;

means for disabling said output signal generating means so that no output signals will be generated despite the presence of activating signals from said electronic digital logic means; and

means connected to said source sensing means for selectively simulating failure of said sources;

whereby the operation of said apparatus can be tested, without tripping or closing the associated circuit interrupters, by disabling said output signal operating means, operating said failure simulation means, and observing said indicating means.

5. Apparatus as recited in claim 4 comprising means for placing said apparatus in a "live test" mode, wherein said disabling means are activated and said indicating means operate in a pulsing manner whenever an activating signal is supplied from said electronic digital logic means to said signal generating means;

whereby operating personnel are informed by the pulsing operation of said indicating means that said apparatus is in the "live test" mode and associated circuit interrupters will not be operated.

6. Apparatus as recited in claim 5 wherein said apparatus is adapted to operate three associated circuit interrupters, and said disabling means selectively disable said output signal generating means to prevent operation of output signals destined for two associated circuit interrupters and allow generation of output signals destined for the third associated circuit interrupter.