background image

Type 

50-DH-50  Air  Circuit  Breaker 

of  the  closing  stroke  the  mechanism  push  rod 
roller  pin  strikes  that  switch  lever  causing  it  to 
rotate  and  permit  the  switch  to  make  contact­

in this case contact is  maintained  when  the circuit 

breaker  is  in  the  latched  position.  On  a  trip-free 
operation the push rod roller pin moves forward to 
engage the vertical leg of the switch lever thus caus­

ing a rotation of  that lever to permit closure of  the 
cut-off switch contacts. 

Latch  Checkin�  Switch 

The  latch  checking  switch,  Figure  14,  mounts 

on the frame by  two screws  as  shown  in the  refer­
ence  figure.  The  switch  operates  directly  from 

Fig.  14-Latch  C 

14 

the  tripping  lever  and  makes  contact  when  the 
tripping  lever  is  in the  normal position  and breaks 
contact when the tripping lever is raised. 

Operation  Counter 

The  operation  counter  mounts  on  the  upper 

auxiliary  switch  bracket.  After  mounting in place 
and connecting to the auxiliary switch extension of 

the breaker lever, the operation counter arm should 
be  loosened  and  set  so  that  only  one  number  is 

recorded for each operation of the mechanism.  This 

setting  should  be  checked  for  both  manual  and 
electrical  operation  of  the  mechanism. 

CAUTION 

Do  not  attempt  to  close  by 
hand,  against  an  energized 
circuit, any  breakers covered 
by  this  instruction  book.  To 
insure 

sufficient 

closing 

force and speed, these break­
ers  should  be  closed  electri­
cally from an  adequate power 
source.  See 

.

E

.

M

.

A

Stand­

ard  SG 

6-213. 

www 

. ElectricalPartManuals 

. com 

Summary of Contents for 50-DG-50

Page 1: ...s 5000 Volts Installation Operation Maintenance INSTRUCTION BOOK CAUTIONS Safety for Personnel Storage Handling Unloading Unpacking Page 6 7 7 Westinghouse Electric Corporation East Pittsburgh Pa I B 32 130 lB w w w E l e c t r i c a l P a r t M a n u a l s c o m ...

Page 2: ...ower air circuit breakers for the past fifteen years Fundamentally a power circuit breaker is a de vice for interrupting a circuit between separable contacts under normal or abnormal conditions Ordinarily circuit breakers are required to operate only infrequently although some classes of break ers are suitable for frequent operations The type DH De ion Air Circuit Breaker is designed to operate in...

Page 3: ...a vertical plate is attached This vertical plate supports the bushings contacts magnetic circuits and arc chambers all of these parts being at high potential Operating Mechanism The electrical operatingmechanismsupplied with this breaker is the direct current solenoid type SAF 2 slightly modified to be adaptable to the ap plication involved This mechanism is mounted so that the moving core operati...

Page 4: ...ned to the top of and project over the stationary main tongues so that they engage the arcing contact surface on the blades as the breaker is opening or closing how ever these arcing contact surfaces do not engage each other when the breaker is in the fully closed position The entire contact arrangement is so de signed that the arcing contacts which have arc resisting surfaces part last on opening...

Page 5: ...t Strap Arcing Secondary Moving Contact Arm Contact Platform Arcing Contact Fig 6 Typical Arrangement of Component Parts 6 to the lower breaker terminal thus relieving the contacts of the current carrying duty until the arc is extinguished in slot of the arc chamber 5 6 SAFETY FOR PERSONNEL The installation operation and maintenance of circuit breaker equipment requires that certain pre cautionary...

Page 6: ...after they have 7 first been made snug In later models the upper cup washer has been replaced with a conical spring and spacer arrangement in which case the nut should be turned up tight on the spacer and cottered in that position When adjusted in this manner the moving contact blades will separate approximately h inch when the arcing contacts engage There should be a slight clearance between the ...

Page 7: ...cumulated in the air line will not be sprayed over insulating surfaces Direct the air stream thoroughly into all joints and crevices If com pressed air is not available this cleaning may be done with a clean dry cloth Steam waste is not recommended for this purpose because of its tend ency to leave a residue of lint on insulating surfaces 8 Magnetic Circuit The magnetic circuit assembly consists o...

Page 8: ...G L V R SPRING TOP PLAT MOVING COR PUSH R O D B OTTOM PLAT MOVING COR SUPP ORT COR GU I D TUB Fig 7 Type 50 DH 50 Electrical Operating Mechanism AUXILIARY SWITCH ARM OPERATING COUNTER OPERATI ON COUNTER ARt l AND CLOSING L V R RIP ATTACtiM NT MOUNTING BOLT UXILIARY SWITCH INGLE COIL HUNT TRIP t J 0 b i a E l e c t r i c a l P a r t M a n u a l s c ...

Page 9: ...uipped with a Rectox unit on alternating current It is a mechanically full automatic mechanism and is trip free in all positions An electrical closing operation 10 is secured by energizing the closing coil A magnetic flux generated by the closing coil forces the moving core and attached push rod upwards against the push rod roller located at the junction of the breaker lever links and the mechanis...

Page 10: ...erload continues an oil dashpot delaying device is attached to the end of the moving core The calibration is inscribed on the dashpot and is varied by screwing the pot into the cover Time is varied by changing the number of holes in the bottom of the piston uncovered by the dia phragm Instantaneous tripping is possible because the check valve action of the washer at the time of tripping varies inv...

Page 11: ...oltage reset spring retrieving the armature to its fully closed position Failure to reset the undervoltage armature completely will result in im proper operation as the holding coil is not capable of picking up the armature The turn buckle should clear the undervoltage armature during the tripping movement The turn buckle should be set to secure Ys clearance be tween the end of the slot in the mec...

Page 12: ...he control switch is reclosed while the breaker is in the latched position the moving core will move to the closed position 13 The cut off switch supplied on the later models is mounted on the right side of the mechanism frame just back of the auxiliary switch Figure 13 shows the position of the switch when the mecha nism is latched closed The switch used in this case is also a normally closed swi...

Page 13: ...ing lever and makes contact when the tripping lever is in the normal position and breaks contact when the tripping lever is raised Operation Counter The operation counter mounts on the upper auxiliary switch bracket After mounting in place and connecting to the auxiliary switch extension of the breaker lever the operation counter arm should be loosened and set so that only one number is recorded f...

Page 14: ... is best accomplished in the following manner 1 Wash with normal heptane obtainable from the major oil companies such as Esso Standard Use clean paper towels wet in the heptane Use a fresh towel on each part Caution Heptane is inflammable and no open flames or sparks should be allowed near the work 2 After the heptane has evaporated which re quires only a minute or two wash with de ionized water s...

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