Claims
- 1. A circuit breaker operative to detect an overcurrent flowing through a main circuit between an AC source and a load, and to perform an overcurrent tripping function, said circuit breaker further comprising:
- a pre-alarm circuit with such a pre-alarming function as to generate an alarm output signal before a current flowing through a main circuit exceeds an overcurrent;
- a pre-alarm signal output circuit driven by said alarm output signal from the pre-alarm circuit and being operative to generate at least one of an audio and visual alarm; and
- a photo-coupler coupled between said pre-alarm circuit and said pre-alarm signal output circuit and being operative in such a direction as to block the transmission of a signal from the pre-alarm signal output circuit to the pre-alarm circuit.
- 2. The circuit breaker as defined in claim 1 wherein said pre-alarm circuit produces the pre-alarm signal, when the main circuit current exceeds a value not larger than 70% of a rated current value.
- 3. The circuit breaker as defined in claim 1 wherein said photocoupler comprises a light emission diode coupled to said pre-alarm circuit and a phototransistor coupled to said pre-alarm signal output circuit.
Priority Claims (1)
Number |
Date |
Country |
Kind |
63-168996 |
Jul 1988 |
JPX |
|
Parent Case Info
This is a continuation of application Ser. No. 07/376,462 filed July 7, 1989 now abandoned.
US Referenced Citations (6)
Foreign Referenced Citations (4)
Number |
Date |
Country |
0045286 |
Feb 1982 |
EPX |
3501353 |
Jul 1986 |
DEX |
2497013 |
Jun 1982 |
FRX |
2564648 |
Nov 1985 |
FRX |
Continuations (1)
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Number |
Date |
Country |
Parent |
376462 |
Jul 1989 |
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