Step down transformer power supply with short circuit protection

Details Step down transformer power supply with short circuit protection Step down transformer power supply with short circuit protection

1995-03-24

1996-10-01

Gaffin, Jeffrey A.

Electricity: electrical systems and devices

Safety and protection of systems and devices

Transformer protection

361104, H02H 704

Patent

active

055615767

ABSTRACT:
A step down transformer power supply with short circuit protection which uses a minimal size transformer, as opposed to an energy limiting transformer. The transformer is mounted directly on a PC board without additional mounting hardware, and has a fuse in its secondary winding, which is required to pass a UL short circuit test, and is normally nonreplaceable. A low cost circuit limits the current output of the transformer such that the fuse is not blown, even under a shorted output condition, which would normally require replacement of the transformer. A rectifier circuit is coupled across the secondary winding of the step down transformer, and is coupled to a first terminal of a three terminal power regulator circuit which supplies a regulated stepped down voltage through a second terminal connected to a load. The third terminal thereof comprises a current/voltage limiting control terminal. A resistor is coupled in series with the load to sense the output current through the load, and is connected to the base of a transistor having an emitter, collector, and base. The collector and emitter of the transistor are coupled in series with the control terminal of the power regulator circuit, such that as the output current increases above a threshold indicative of a short, the output current of the power regulator is limited to prevent the slow-blow fuse from being blown.

REFERENCES:
patent: 3691425 (1972-09-01), Weyrich et al.
patent: 4175250 (1979-11-01), Morgan
patent: 4855892 (1989-08-01), Lower

Affiliated with

Also associated with

Rating

Step down transformer power supply with short circuit protection does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Step down transformer power supply with short circuit protection, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Step down transformer power supply with short circuit protection will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-1506670