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Westinghouse DB-75 Instructions Manual Download Page 3

I. B.  35-240-1 

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LIST  OF  ILLUSTRATIONS 

DB-75  Outline  and  Mounting  Dimensions 

Typical  Wiring  Diagrams 

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Cross-Sectional  View  of  Type  DB-75  Circuit  Breaker 
Adjusting  Limits  of  Main  and  Arcing  contacts  for  DB-75 

Circuit  Breakers  . 

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Closing  Solenoid  - Construction  Details 

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Cross-sectional  View  of  Overcurrent  Tripping  Device  with 

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Long  Delay  and  Instantaneous  elements 

Schematic  and  Typical  Time-Current  Characteristics  of 

OVercurrent  Tripping  Device  with  Long  Delay  and 

Instantaneous  Elements  .  .  .  .  .  .  . 

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Cross-Sectional  View  of  OVercurrent  Tripping  Device  With 

Long  Delay  and  Short  Delay  E lements 

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Schematic  and  Typical  Time-Current  Characteristics  of 

lOA 

lOB 

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Overcurrent  Tripping  Device  with  Long  Delay  and  Short 

De lay  Elements  .  .  .  .  .  . 

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Schematic  Diagram  of  Overcurrent  Tripping  Device  with 

Instantaneous  Element  Only  .  .  .  .  .  .  .  .  .  .  .  .  . 

Typical  Time-Current  Characteristics  of  overcurrent  Tripping 

Device  with  Instantaneous  Element  Only  . .  

Control  Relay  - Construction  Details  .  .  .  .  .  .  .  . 
Shunt  Trip  Attachment  - Construction  Details  .  .  .  . 
Undervoltage  Trip  Attachment  - Construction  Details 
Undervoltage  T ime-Attachment  - Construction  Details 
Auxiliary  Switch  - Construction  Details  .  .  .  .  .  . 
Alarm  Switch  Attachment  - Construction  Details  .  .  . 

Electrical  Lock-Out  Attachment  - Construction  Details 
Key  Lock  or  Key  Interlock  Attachment  - Construction  Details 
Rectifier  Unit  for  A-C  Undervoltage  and  A-C  Electrical 

Lockout  Attachments  .  .  .  .  .  .  .  .  . 

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Summary of Contents for DB-75

Page 1: ...s A C 250 Volts D C INTERRUPTING RATING 75 000 Amperes 600 Volts A C 100 000 Amperes 250 Volts A C November 1956 I B 35 240 1 I WESTINGHOUSE ELECTRIC CORPORATION i 11 Switchgear Division East PittSburgh Plant eel East Pittsbu gh a Jil Ji 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: ...tion 4 Time current Characteristics 5 Adjustment of Calibration Settings 6 Maintenance Control Relay Shunt Trip Attachment Undervoltage Trip Attachment Undervoltage Time Delay Attachment Auxiliary Switch Alarm Switch Attachment Electric Lockout Attachment Key Lock Attachment Key Interlock Attachment Rectifier Unit for A C Undervoltage and A C Electric Lockout Attachments 7 11 11 12 12 12 12 15 15 ...

Page 3: ... lOA lOB 11 12 13 14 15 16 17 18 19 Overcurrent Tripping Device with Long Delay and Short Delay Elements Schematic Diagram of Overcurrent Tripping Device with Instantaneous Element Only Typical Time Current Characteristics of overcurrent Tripping Device with Instantaneous Element Only Control Relay Construction Details Shunt Trip Attachment Construction Details Undervoltage Trip Attachment Constru...

Page 4: ...I B 35 240 1 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 5: ...mounted in an enclosure suitable to local operating conditions A selection of standard enclosures is available for various applications IMPORTANT To assure proper functioning inspect each breaker at regular intervals in accordance with a systematic maintenance schedule The frequency and character of the inspections will for the most part be determined by the severity of the duty performed The mini...

Page 6: ...ns for proper operation should therefore be made with the breaker in this position Final inspection should preferably b e made with the breaker in its permanent mounting 6 2 Remove anyforeign particles from the hinge end of the moving contacts 3 Insert the maintenance operating handle and slowly close the breaker a Observe whether all parts are in proper alignment and move freely b Be sure that th...

Page 7: ...s and 3 completing any secondary control w iring that may be necessary CAUT ION DUR ING INSTALLAT ION THE C IRCU IT BREAKER SHOULD BE IN THE OPEN POS IT ION Be sure to de energize the load and control leads to be connected and also the section of the switchboard where installation is being made Mounting dimensions and details of the front enclosure cutouts are shown in Figure 1 To prevent distorti...

Page 8: ... BUILDER 1 J l I li 10 II I I riJ POSITION INDICATOR ADDITIONAL 4 POLE AUXILI ARY SWITCH 4 POLE AUXILIARY SWITCH Z4 DIA 6 MOUNTING HOLES f J 2 LIFTING BRACKET DOOR OR FRONT COVER SUPPLIED BY SWITCHBOARD BUILDER BOUNDARY SURFACES OF THE CIRCUIT BREAKER ARE TO BE CONSIDERED GROUND POTENTIAL PROVISION FOR PADLOCKING BREAKER L IN TRIPPED POSITION PADLOCKS FURNISHED BY CUSTOMER FIG 1 DB 75 OUTLINE AND ...

Page 9: ... O OI 2J x coNTROL RE LAY 1 0 G 1 1 460 VAG 1 810317 o 03J cc cLOSING COIL I J FUSES TC TRIP COIL 125VDC X I T GONT V RATING cs coNTROL SWITCH 250VDC c I 2oe VAC R RED LAMP CLOSED 208VAC X l 230 VAG 4 0A 600V G GREEN LAMP OPEN g 4 TC 460 VAG U V UNDER V OLTAGE 125 VAG 30A 250V LO LOCKOUT l 1 250 VAG 15A 250V AS ALARM SWITCH o o MAKE CONTAC _r _yg _ bZ b BREAK CONT _ b __ CONTROL VOLTAGE SCHEMATIC ...

Page 10: ...00 VOLTS A C CLOSING SOLENOID POLE UNIT MECHANISM CLOSED ARC CHUTE ALUMINUM PANEL TRIPPED OVERCURRENT TRIPPING DEVICE OPEN RESET FIG 3 CROSS SECTIONAL VIEW OF DB 75 CIRCUIT BREAKER 10 I B 35 240 1 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 11: ...lowing order 1 Turn adjusting n uts A on insulating links to vary main contact pressure Use 005 feeler gauge 1 4 inch wide by 6 inches long inserted as shown in Figure 4A to check clearance Feeler X above contact fingers insures that they have all been deflected Feeler Y inserted below fingers insures that they have not gone solid 2 Check clearance between cam B and roller C located between insula...

Page 12: ... up and then drive the pin to the right just far enough to clear the moving core rod Lower the moving core until it hits its stop Drive the pin to the left into its original posi tion 5 Remove the four mounting bolts a CAUTION THESE BOLTS ARE ALSO THE MOUNT ING BOLTS FOR THE CLOSING SOLENOID THEREFORE SUPPORT THE SOLENOID WHILE REMOVING THE BOLTS n Remove the Mechanism The mechanism is factory 1 u...

Page 13: ... I I I I I I Jl_ I I I II I I 1 I I II 1 I I II I I I II I I I 1 II I 1 I II I I 1 I II I 11 I I II I I II II I I I I II II II I I II I r I I II I I I I I II I I I I II I 1 I II I I I l i I i i I l11 u l II II o II C I i l II II I I 0 l t til I II Jt I I I II I 0 z 0 n 0 n c l til 0 i l i l 0 w E l e c t r i c a l P a r t M a n u a l s c o ...

Page 14: ...INSTA NTANEOUS PICK UP CAL IBRATION SPRING INSTANTANEOUS STAT IONARY MAGNE T t LONG DELAY STAT IONARY MAGNET t r I L L 7 v rT I t I L _ J l j h r _ __ __ LOW I r ER BREAKER STUDS I I j i L r J k _POLE UNI T BASE CJ 1 1 I i DIAPHRAGM AIR FILTER LONG DELAY VALVE AND DIAL FIG 6 CROSS SECTIONAL VIEW OF OVERCURRENT TRIP PING DEVICE WITH LONG DELAY AND INSTANTANEOUS ELEMENTS a z tzl z z tzl w E l e c t ...

Page 15: ...ly equal when the main armature is closed Then tighten all four mounting bolts securely Adjustment of Trip Screw The trip screw mounted on the trip finger must be adjusted properly to obtain proper tripping CAUTION SINCE THIS ADJUSTMENT INVOLVES TRIPPING THE BREAKER CARE MUST BE TAKEN TO KEEP FINGERS AND FACE AWAY FROM ALL CONTACT ARMS AND OPERATING LINKAGE To proceed with the adjustment turn the ...

Page 16: ...ANEOUS PICK UP CALIBRATION SPRING R BREAKER MOVING CONTACT ARM W SHAFT 11 LONG DELAY PICK UP ADJUSTMENT RESETTABLE DELAY f LONG DELAY TIME ADJUSTMENT GUIDE BEARING _j_ SOLID JOINT PINNED JOINT I 1 NO JOINT mJm_ STOP SURFACE Q ADJUSTABLE SCHEMATIC DIAGRAM 16 CURRENT MAGNITUDE TYPICAL TRIPPING CHARACTERISTICS FIGURE 7B FIGURE 7A FIG 7 SCHEMATIC AND TYPICAL TIME CURRENT CHARACTE RISTICS OF OVE RCURRE...

Page 17: ...ER LONG DELAY ARMATURE T DELAY ARMATURE PART S WHICH DISCRIMINATE BETWEEN A BREAKER IN CLOSED POSITION B BREAKER OUR lNG PERIOD OF C LOSING L ARRANGED FOR LONG DELAY AND SHORT DE LAY TRIPPING ARRA NGED FOR LONG DELAY AND INSTA NTANEOUS TRIPPING o 0 t l t l o l t l t l 0 z a n a n c o l a t l t l a w E l e c t r i c a l P a r t M a n u a l s c o ...

Page 18: ...OR T DEL A Y OVER TRAVEL SPRING LONG DELAY FORCE LIM ITING SPRING LONG DELAY PICK UP CALIBRATION SPRING SHORT DELAY PICK UP CALIBRATION SPRING _ __ j j __L WE BREAKER t I STUDS I ME J j I DISCRI PISTON MINATOR Tl I DELAY L_ _ f POL E UNIT BASE r 1 w N J DIAPHRAGM AIR FILTER SHORT DELAY VALVE __ LONG DELAY VALVE AND DIAL FIG 8 CROSS SECTION AL VIEW OF OVERCURRENT TRIP PING DEVICE WITH LONG DELAY AN...

Page 19: ... A BREAKER MOVING CONTACT ARM S DISCRIMINATOR ROLLER T DISCRIMINATOR TIME DELAY PISTON U DISCRIMINATOR LEVER V DISCRIMINATOR LATCH W SHAFT I I t 1 LONG DELAY PICK UP ADJUSTMENT RESETTABLE DELAY I I I I I I I I I I I TOTAL CLEARING TIME f t LONG DELAY TIME ADJUSTMENT DELAY PICK UP ADJUSTMENT GUIDE BEARING _j_ SOLID JOINT PINNED JOINT NO JOINT 1 STOP SURFACE ADJUSTABLE SCHEMATIC DIAGRAM CURRENT MAGN...

Page 20: ...ring C which is restrained by diaphragm D until sufficient air has entered valve P to permit the spring assembly C to lift crank J and trip the breaker by ro tating the trip finger K A discriminator arm is used on the selective overcurrent trip units to make the unit behave as an instantaneous type trip unit while the breaker is being closed and for a short inter val of time after closing This is ...

Page 21: ...resents the minimum time for the breaker to clear when fault currents exceed ten times the trip unit rating S ELECTIVE OVERCURRENT TRIPPING DEVICE Refer to Figure 9B The time current characteristic of this trip unit is the same as the standard device except that the position of the flat portion of the curve can be shifted as indicated by the number 3 This adjustment can be made b y changing the se...

Page 22: ... dl_____ l fF r ll 4 I u _ I RELAY TOGGLE _ Lt ARC j RELEASE CHAMBER RElAY TRIP J CLOSING SOlENOID BRACKET MOVING CORE A C OPERATING SOLENOID C8J l STATIONARY CONTACT D C OPERATING SOLENOID RELAY TRIP PIN BLOWOUT COIL FIG 1 1 CONTROL RELAY CONSTRUCTION DETAILS J z z z n E l e c t r i c a l P a r t M a n u a l s c ...

Page 23: ...igure 12 mounts on top of the platform immediately to the right of I I I I I I I 0 I I I the operating mechanism It is non adjustable and is intended for intermittent duty only The shunt trip circuit must always be open by an auxiliary switch contact Inspecti on With the breaker in the open position m anually pull the shunt trip moving core against the stationary core and manually at tempt to clos...

Page 24: ...rotates the pin pushes against the latch to release it from its latch plate When the latch releases the trip spring rotates the trip lever to trip the breaker The linkage is reset by the c ross bar as the breaker opens Always connect the coil to the line side o f the breaker unless the attachment is equipped with time delay device In this case the time delay will delay the tripping of the breaker ...

Page 25: ...D C 2 1 75 115 v A C 75 15 450 v A C 25 5 Inspection Hold the U V trip lever down and close the breaker manually Release the trip lever slowly allowing the undervoltage trip spring to rotate the trip rod and trip the breaker after a time delay CAUTION DO NOT USE YOUR FINGERS TO HOLD AND RELEASE THE U V RESET LEVER Maintenance Check for loose bolts and faulty coils The switch is a shaft operated 4 ...

Page 26: ...Note that the alarm contacts do make contact Maintenance Clean the alarm contacts when necessary Check for loose bolts 26 ELECTR IC LOCKOUT ATTACHMENT The electric lockout Figure 17 mounts on the top of the platform on the extreme left side and behind the auxiliary switches Its function is to hold the breaker open trip free until the lockout coil is energized The lockout coil can be de energized a...

Page 27: ...35 240 1 TYPE DB 75 DE ION AIR CIRCUIT BREAKER I I r I C _ lli____ _ 1 w Q z 0 i u l et f z 0 u 1 z w z u I z u 1 V et J ci u 27 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 28: ...MAINTENANCE rr I ll_ 28 H M1 T IT V J 1 w Cl z 1 L V l z 0 Ul 1 z w e c u 1 5 I u 0 l l C u e 1 u w l w _ ci LL B 35 240 1 I 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 29: ... B 35 240 1 TYPE DB 75 DE ION AIR CIRCUIT BREAKER ln I I I I I J LRfl I I V J 1 w 0 z 0 1 u 0 I V z 0 u 1 z w 1 u 1 u 0 J 0 w 1 z w 0 0 u 0 J w u 29 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 30: ...key interlock attachment the key cannot be removed unless the breaker is locked in the open position Inspection Push the trip button and turn key to the locked position The key is then removable and the breaker is locked in the trip free position Replace the key and rotate to the 30 RECTIFIER UNIT FOR A C UNOERVOLTAGE AND A C ELECTRIC LOCKOUT ATTACHMENTS When an a c undervoltage attachment or an a...

Page 31: ..._ _ iEf4 i I II II u TERMINAL BLOCK RECTIFIER TO UV AND OR LO TRANSFORMER TO AC VOLTAGE SOURCE SCHEMATIC FIG 19 FIG 19 RECTIFIER UNIT FOR A C UNDERVOLT AG E AND ELECTRICAL L OCKOUT ATT ACHMENTS _ _ _ ________ _ ____ ___ _ ___ o o i CC l l t 1 til t 1 l l 0 z a a c o i til a l l l l a E l e c t r i c a l P a r t M a n u a l s c ...

Page 32: ...t l J f f w m _ r W Cfttz 7 jHS R u 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 ...

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