Electricity: measuring and testing – Electromechanical switching device – Relay
Patent
1991-04-15
1993-07-13
Wieder, Kenneth A.
Electricity: measuring and testing
Electromechanical switching device
Relay
324418, 340644, G01R 3102, G08B 2100
Patent
active
052277291
DESCRIPTION:
BRIEF SUMMARY
DESCRIPTION
1. Technical Field
This invention relates to a fusion detecting system for relays for detecting a fusion of relay contacts, and more particularly, to a fusion detecting system for relays for detecting a fusion thereof by using semi-interlocked or fully-interlocked relays.
1. Background Art
Contacts of relays, magnets, or the like are sometimes fused together by an extreme current overload or contamination due to long use, and if these relays or magnets are used to produce a safety signal for a PC (programmable controller), etc. which controls a machine tool, for example, an emergency stop signal, or an interlock signal associated with a splash guard of the machine tool, the operator may be exposed to unexpected danger. Accordingly, to avoid this danger, semi-interlocked or fully-interlocked relays are used.
In semi-interlocked relays, if a make contact is fused during a current supply to the coil, the other contact is held in an open state or at a make-contact side after the current supply to the coil is cut off. On the other hand, if a break contact is fused, the other contact is held in an open state or at a break-contact side after a current supply to the relay coil is started.
In fully-interlocked relays, if a make contact is fused during a current supply to the coil, the other contact is held in a make-contact state after the current supply to the coil is cut off, and if a break contact is fused, the other contact is held in a break-contact state after a current supply to the relay coil is started.
Nevertheless, even when these relays are used, danger cannot be avoided if the fused contact is used to produce an emergency stop signal or the like.
Usually, the movement of the contacts of these relays, etc., is too minute to be observed with the naked eye, and since the relays are generally housed in the casing of a control device, the movement or non-movement of a contact cannot be determined from the outside.
DISCLOSURE OF THE INVENTION
This invention has been created in view of the above circumstances, and an object thereof is to provide a fusion detecting system for relays by which a fusion of relays can be reliably detected.
To achieve the above object, according to this invention, there is provided a fusion detecting system for relays wherein two fully-interlocked or semi-interlocked relays are connected in such a manner that they operate under identical conditions, and a fused state is detected based on the states of signals sent from series-connected make contacts and series-connected break contacts of the two relays.
In semi-interlocked relays, if a make contact is fused during a current supply to the coil, the other contact is held in an open state or at a make-contact side after the current supply to the coil is cut off, and if a break contact is fused, the other contact is held in an open state or at a break-contact side after a current is supplied to the relay coil.
In fully-interlocked relays, if a make contact is fused during a current supply to the coil, the other contact is held in a make-contact state after the current supply to the coil is cut off; if a break contact is fused, the other contact is held in a break-contact state after a current is supplied to the relay coil.
Accordingly, two semi-interlocked or fully-interlocked relays are used under identical conditions, the make contacts and break contacts of the relays are individually connected in series, and signals sent therethrough are checked to thereby detect a fusion of the relays.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a circuit diagram illustrating a relay checking system according to this invention;
FIG. 2 is a diagram illustrating a ladder program for detecting a fusion of relays; and
FIG. 3 is a diagram of a logic table used for detecting a fusion of relays.
BEST MODE OF CARRYING OUT THE INVENTION
One embodiment of this invention will be described with reference to the drawings.
FIG. 1 is a circuit diagram showing a relay checking system according to this invention, in which a PC (programmable co
REFERENCES:
patent: 3548399 (1970-12-01), Monigal et al.
patent: 3575607 (1971-04-01), Edstrom
patent: 3587096 (1971-06-01), Teichmann
patent: 4516076 (1985-05-01), Pillari et al.
patent: 4546224 (1985-10-01), Mostosi
patent: 4645886 (1987-02-01), Williams
patent: 4647727 (1987-03-01), Sontheimer
patent: 4767941 (1988-08-01), Brand et al.
patent: 4914315 (1990-04-01), Nickolai
Patent Abstracts of Japan, vol. 5, No. 183 (M-097), Nov. 21, 1981; & JP-A-56 103 013 (Mitsubishi) Aug. 17, 1981.
Patent Abstracts of Japan, vol. 11, No. 254 (E-533), Aug. 18, 1987; & JP-A-62 064 (Sumitomo) Mar. 23, 1987.
Fanuc Ltd
Regan Maura K.
Wieder Kenneth A.
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