Transfer switch position sensing using coil control contacts

Details Transfer switch position sensing using coil control contacts Transfer switch position sensing using coil control contacts

1999-04-12

2001-10-02

Metjahic, Safet (Department: 2858)

Electricity: measuring and testing

Electromechanical switching device

Reexamination Certificate

active

06297640

ABSTRACT:

BACKGROUND OF THE INVENTION
This invention relates to an apparatus and method for determining the state of an automatic transfer switch. More specifically, the invention is directed to a method of, and the construction of apparatus for, determining the position or state of an automatic transfer switch from voltages readily available without need for special switch position contacts.
An electronic control circuit for an automatic transfer switches must monitor the position of the transfer switch in order to initiate proper action in response to a power outage or restoration. It is known in the art to provide an automatic transfer switch with auxiliary position contacts for determining the state or position of the switch. The control circuit is operatively connected to the position contacts for determining whether the contacts are open or closed. Because the auxiliary position contacts are mechanically linked to the main contacts, the state of the switch can be determined.
The use of auxiliary contacts is inefficient and expensive. The contacts themselves and their inclusion in the structure of an automatic transfer switch are costly. Moreover these contacts are subject to wear and breakage. In addition, special circuitry must be connected to the contacts to monitor their open/closed state.
SUMMARY OF THE INVENTION
The aforementioned problems of the prior art are overcome by the instant invention which provides a method for determining the state of an automatic transfer switch from voltages measured across the normal and alternate source contacts and normal and alternate source coil control contacts of the switch which are inherent in and necessary to the function of an automatic transfer switch, without need for auxiliary switch position contacts.
The invention teaches a method of determining the state of an automatic transfer switch having output contacts connectable to an electrical load, normal source contacts connected to a normal source of voltage, alternate source contacts connected to an alternate source of voltage, main contacts movable between a normal position at which the main contacts are connected to the normal source contacts and an alternate position at which the main contacts are connected to the alternate source contacts, an electromechanical actuator operatively connected to the main contacts for moving the main contacts between the normal position and the alternate position, normal coil control voltage contacts connected to the actuator and connectable to the normal source of voltage for inducing the actuator means to move the main contacts to the alternate position, and alternate coil control voltage contacts connected to the actuator and connectable to the alternate source of voltage for inducing the actuator to move the main contacts to the normal position. According to the invention, an electrical control circuit determines whether there are voltages across the contacts of the normal source contacts, the alternate source contacts, the normal coil control voltage contacts, and the alternate coil control voltage contacts, respectively, and produces a signal indicating the position of the main contacts as a function of the foregoing determinations.
It is therefore an object of the invention to determine the position of the main contacts of an automatic transfer switch without need for special position contacts on the switch.
Another object of the invention is to determine the position of the main contacts of an automatic transfer switch by monitoring voltages used in connection with the function of the switch.
Still another object of the invention is to determine the position of the main contacts of an automatic transfer switch by monitoring voltages at the normal source voltage contacts, the alternate voltage contacts, the normal source coil control voltage contacts and the alternate source coil control voltage contacts.
A further object of the invention is to detect when an error condition exists in monitoring voltages used in connection with the function of an automatic transfer switch to determine the position of the switch's main contacts.
Other and further objects of the invention will be apparent from the following drawings and description of a preferred embodiment of the invention in which like reference numerals are used to indicate like parts in the various views.


REFERENCES:
patent: 5736594 (1998-04-01), Sheppard et al.

Affiliated with

Also associated with

Rating

Transfer switch position sensing using coil control contacts does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Transfer switch position sensing using coil control contacts, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Transfer switch position sensing using coil control contacts will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-2599452