Friday Picture

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brian john

Senior Member
Location
Kilmarnock, Va
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Retired after 52 years in the trade.
This is a picture of a Bolt Switch with a broken operator, the switch is partially closed and won't open or close. Note in the real time picture the open actuator is hanging out a bit.

This switch is part of a Main Tie Main switchgear normally they operate with this Main carrying all the load, with the Tie closed and the other Main open..

More weekend work

The DANGER HANDLE TRIP HAZARD is due to the fact that when a Bolt Switch opens the handle moves with some force.
We know this but obviously someone did not.





BROKENBOLTSWITCH.jpg
 
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Marc: This is a BoltSwitch

Bolted pressure switches have a cam that tightens the movable blades on the stationary blades when they reach the final closed position. When you open the switch the cam operates first loosening the tension on the blades allowing ease of opening.

There are two styles of bolted pressure switches non-charged and charged spring closing and opening. The three common bolted pressure switches (at least around here) are Pringle, Bolt Loc and BoltSwitch.

The bolted pressure switch operator is comprised two sets of springs (in the case of Pringle a series of coned shaped washers that are compressed much like a spring). These are used to close and open the switch (Pringle calls these CBC {Charge Before .Closing}); the springs are charged by operations of the front handle.

This permits very fast operations of the switch, which is necessary in ground fault and phase to phase faults (when the switch is fitted with these OCP functions). The switch can be fitted with a variety of methods of opening, GFP (ground Fault Protection) Blown fuse trip (a type KAZ fuse is parallel with the power fuse if the power fuse blows the KAZ blows), the KAZ has a spring actuator that pops up to close a micro switch and open the switch, Phase Relays, Under Voltage Relays, Reverse phase Relays ECT?.

In addition capacitor trip devices are furnished as part some of the options listed above to permit opening with lose of power on the control circuit.

I'll attached photos on Monday
 
brian john said:
Bolted pressure switches have a cam that tightens the movable blades on the stationary blades when they reach the final closed position. When you open the switch the cam operates first loosening the tension on the blades allowing ease of opening.
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Sounds like the jaws in a bypass-type meter base.
 
George: I forgot the Main Tie Main question:

In this situation there are two utility 13.8 KV feeders to two fusible air break switches these in turn feed two 13.8 delta to 480 wye transformers. The secondary of the transformers feed the two Main Service Disconnects. Each Main can carry the complete load of the building. But the load is split into two switchboards one switchboard feeds the east wing the other switchboard feeds the west wing. Between the two switchboards is a Tie breaker this is a manual operated switch (though automatic versions are available). Should either switchboard feeder experience an outage, the effected Main can be opened and the Tie can be closed and the power to the switchboard restored. This is an open operation so when utility service is restored to the dead service, it will require opening the Tie which de-energizes the one side, till the Mian can be closed. Noit a long period but this is usually completed off hours.

This (and hopefully most) Main Tie Main have Kirk Key Interlocks* that is the Tie cannot be closed if both Mains are closed; You have to open a Main to remove the key that permits you to close the Tie.


* Kirk Key is a company name and has become a generic term for keyed interlocks.

http://www.kirkkey.com/
 
The Kirk key also seems to be the single most misplaced key by building engineers. They usually put it in a place where they won't forget where it is. :D
 
Why would a Kirk key be lost? The systems that I have worked on, the key had to be left in one of the two locks.
Don
 
don_resqcapt19 said:
Why would a Kirk key be lost? The systems that I have worked on, the key had to be left in one of the two locks.
Don
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When used in an interlock configuration, such as Brian's double ended switchboard, yes. They're used for other things too. Permanent LOTO is one of them. Sometimes, you need the "main key" from the office or where ever it is kept to put into the circuit breaker's double-keyway lock to start the whole process of the transfer. (like a bank safe deposit box, where the manager uses his/her key also)
 
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We have had a few jobs where the keys were broken, due to misunderstandings of the system operation. In one case the complete operation was spelled out in simple terms, the excuse, "Oh I did not read that"
 
brian john said:
We have had a few jobs where the keys were broken, due to misunderstandings of the system operation. In one case the complete operation was spelled out in simple terms, the excuse, "Oh I did not read that"
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Nice. Like, "I couldn't figure out why that darned key was stuck, so I used a pair of vice grips on it". :grin:

This is they key I was talking about getting misplaced:
Kirk Key Paper 103 said:
For particularly sensitive operations such as when work needs to be performed under more-than-usual supervision, an interlock system may include a "supervisory key". Inserting the normal key alone will not operate the interlock to permit further steps. Instead, a second key (assigned to a designated supervisor) must also be introduced for operation in the same interlock. A "supervisory key" can be introduced at any point of an interlock system regardless of the complexity.
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