Electricity: electrical systems and devices – Safety and protection of systems and devices – With specific current responsive fault sensor
Patent
1996-08-20
1998-02-24
Young, Brian K.
Electricity: electrical systems and devices
Safety and protection of systems and devices
With specific current responsive fault sensor
361115, 361 78, H02H 300
Patent
active
057216576
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to a load control module and in particular to a load control module for controlling switch gear which, in use, connects a power source to a remotely located electrical load.
The invention has been developed primarily for use in underground mining environments and will be described hereinafter with reference to that application. However, it will be appreciated that the invention is not limited to that particular field of use and is also suitable for providing load control for most electrically powered devices such as motors, transformers and the like in both mining and above ground applications.
BACKGROUND ART
Hitherto, high power electrical equipment such as motors and transformers have been connected to a power source via switch gear. This switch gear is in general set up for a particular piece of equipment so that once certain predetermined load characteristics vary sufficiently the power will be disconnected to prevent any potentially hazardous conditions which may result in the loss of equipment or life. Any set up or adjustment of the switch gear must be manually performed which, due to operator fatigue or inadvertence, may result in incorrect adjustment.
In underground mining applications the switch gear is preferably located within a protective housing to ensure that any sparks generated during switching are not available to ignite flammable gases such as methane which may be present. Such housings include walls formed from thick steel plate and which are accessible through an opening which is closed by a door. Such doors are generally attached about their periphery to an adjacent wall by a plurality of spaced apart bolts. Accordingly, to set up or adjust the switch gear for a particular piece of equipment necessitates the opening of the steel door by removing all the bolts, the setting of the switch gear, and the subsequent replacement of the door. Following this procedure testing should be conducted to ensure safe operation. If the switch gear is not correctly set this process must be repeated. Accordingly, any reconfiguration is both time consuming and labour intensive.
It is an object of the present invention, at least in its preferred embodiment, to overcome or substantially ameliorate at least some of these deficiencies of the prior art.
DISCLOSURE OF INVENTION
According to the invention there is provided a load control module for controlling switch gear which, in use, connects a power source to a remotely located electrical load, the module including: indicative of predetermined operating parameters of the load; and a second signal to the switch gear to isolate the load from the power source when said load does not comply with said parameters.
Preferably, the switch gear and the controller are located within a protective housing and the sensor unit and load are disposed outside the housing.
Preferably also, the sensor unit periodically provides a third signal indicative of predetermined load conditions. More preferably, the sensor unit provides the third signal when requested by the controller.
In a preferred form, the controller and sensor unit communicate through a single wire communication link which also supplies power to the sensor unit. More preferably, the switch gear selectively connects the power source to the load via an appropriate power cable, the cable including the communication link.
BRIEF DESCRIPTION OF DRAWING
A preferred embodiment of the invention will now be described, by way of example only, with reference to the accompanying drawing in which:
FIG. 1 is a schematic representation of a control module according to the present invention.
BEST MODE OF CARRYING OUT THE INVENTION
Referring to the drawing (not to scale), a load control module 1 controls switch gear 2 which, in use, connects an AC power source 3 to a remotely located load 4 which can be a motor, transformer, any other piece of electrical equipment or a number of pieces of such equipment. Module 1 includes a sensor unit 9 which is mounted on load 4 for pro
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Mittra et al., "Thermistor Based Pilot Relay Scheme for Protection of Coal Face Electrical Drives", Mining Technology, Jan. 1987, pp. 5-7.
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Fidyk Roman
Gibbons Eric Gayne
Griffiths Gregory Mark
Weaver John William
Jackson Stephen
Metal Manufactures Limited
Young Brian K.
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