Westinghouse RC Instructions Manual Download

Page: 17 / 114

INSTALLATION

•

Westinghouse

I.L 4 1 -66 1 E

OPERATION

•

MAINTENANCE

I N S T R U C TI O N S

TYPE RC AUTOMATIC RECLOSING RELAY

C AUT I O N

Before putting relays into service, remove

all blocking which may have been inserted for the
purpose of securing the parts during shipment, make

sure that all moving parts operate freely, inspect the
contacts to see that they are clean and close prop

erly, and operate the relay to check the settings and

electrical connections.

A P P L I C A T I O N

The type RC automatic reclosing relay is used

for automatic reclosure of AC or DC electrically oper

ated circuit breakers after they have been opened by
overcurrent or other protective relay action. The relay

may  be  adjusted  to  provide  several  reclosures  at  pre
determined  time  intervals,  so  that  in  case  the  breaker
does  not  remain  closed  after  the  first  reclosure  addi
tional  reclosures  will  be  made.  The  first  reclosure

usually  is  an  instantaneous  reclosure  through  pre
closed  contacts  since  system  operating  experience
has  shown  that  the  majority  of  faults  are  of  a  tem
porary  nature,  such  as  lightning  flashovers,  and  will

not be re-established after interruption of the fault
current. Consequently, service interruption can be

minimized by the use of an instantaneous reclosure.
However, the first reclosure may be delayed if desired.

In case the circuit breaker does not remain closed

after the first reclosure, the relay will make additional
reclosures at suitably graded intervals. It is common

practice to make two additional reclosures, but the
relay may be adjusted to make any number up to a

total of six reclosures if desired. If the breaker does

not remain closed after the final reclosure, the timing

drum  stops  in  the  "Lockout"  position,  and  any  further
attempts  at  reclosure  must  be  made  by  manual  opera
tion  of  the  control  switch.  However,  if  the  breaker

remains closed after any automatic reclosure, or, sub

sequently, after manual reclosure, the relay timing
drum will advance to and stop at the "Start" position,

where the relay is in readiness for another cycle of

automatic reclosures following the next tripping of

the breaker.

For any automatic reclosing application, the de

rating factors for breaker interrupting ability should

SUPERSEDES I. L. 41 -66 1 0

*Denotes ch ange from superseded i ssue.

be checked when choosing any particular reclosing

cycle,  Also,  when  using  instantaneous  first  reclosure
it  is  necessary  that  the  protective  relays  open  their
contacts  within

cycles or less after the breaker

is tripped in order that the trip circuit will be de
energized before reclosure takes place.

CO N S T R U C T I O N

As shown in figure 1, the RC relay consists of a

latching solenoid unit, Y, a synchronous motor driven
timing unit and an instantaneous auxiliary unit,

An additional instantaneous unit, Z, is also provided

when specified.

T im i ng U nit

The timing unit contains a synchronous motor and

gear train mounted behirul the front sub -base. The

gear  train  drives  a  drum  with  cams,  which  actuate
contacts  1,  2,  3, 4  and  14.  Cam  5  actuates  the  Y  unit
latch  to  reset  the  Y  unit  and  close  the  Y13  contact.
Cams  #

and # 2, which operate contacts

and 2

respectively, are notched and are not intended to be
adjusted in the field.

cam #3 is a series of flat

springs secured by screws, which can be located at
any point on the periphery of the drum. Cams #4 and
#5

consist of s crews which can be set at any point on

the periphery of the drum. Cam #14 is

a single

micarta

block, located to the rear of the cam #5 position and

held by a #5 cam screw.

The gear train reduction ratio is adjustable. The