Browse Prior Art Database

Ferroresonant Power Supply Warning Circuit

IP.com Disclosure Number: IPCOM000110273D
Original Publication Date: 1992-Nov-01
Included in the Prior Art Database: 2005-Mar-25
Document File: 2 page(s) / 112K

Publishing Venue

IBM

Related People

Clemmons, E: AUTHOR [+2]

Abstract

Described is a hardware circuit that provides advance warning for three functional elements of a ferroresonant power supply. The circuit combines the three warning functions into one circuit operation. The three functions are: power on reset warning, power/thermal warning and shut down warning designed to shut off the power supply when either a voltage fault or thermal condition occurs.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 52% of the total text.

Ferroresonant Power Supply Warning Circuit

       Described is a hardware circuit that provides advance
warning for three functional elements of a ferroresonant power
supply.  The circuit combines the three warning functions into one
circuit operation.  The three functions are: power on reset warning,
power/thermal warning and shut down warning designed to shut off the
power supply when either a voltage fault or thermal condition occurs.

      The figure shows the circuit implementation for the three
combined warning functions.  The power on reset circuit consists of
comparator 10, timer 11, transistor 12 and their associated resistors
and capacitors.  Upon turning the power supply on, monostable timer
11 produces a high output so as to turn on transistor 12, providing a
low or down level power on reset output.  After a predetermined time
delay, defined by resistor 13, capacitor 14 and internal circuits of
timer 11, the output of timer 11 will go low, causing transistor 12
to turn off and the output of the power on reset line to become high.
Diode 15 prevents the initial down level of the output of comparator
10 from interfering with the turn-on time delay provided by resistor
13, capacitor 14 and timer 11.

      In the event of a fault condition, the output of comparator 10
will switch to a down level, pulling pins 2 and 6 of timer 11 to
a down level.  This action causes the output of timer 11 to go high,
turning on transistor 16 and causing transistor 17 to turn off.  When
transistor 17 turns off, diode (SCR) 18 turns on to provide a power
supply 'crow-bar' function to turn off a power supply input circuit
breaker (not shown).

      Power/thermal warning is provided by diodes 19 and 20,
comparator 21, transistors 22, 23, 24 and 25, and timer 26.  Diodes
19 and 20 are connected directly to one of the transformer secondary
windings (not shown) of the ferroresonant transformer and function
before DC rectification and filtering.  This allows comparator 21 to
turn on rapidly so as to turn on transistor 23 and to turn off
transistor 22, thereby providing the power warning signal.  Upo...