Definition: Switch / disconnect 1

[collies99]

I am writing a MV substation commissioning course.

Can anyone direct me to the most complete place to look for definitions for the power disconnects (switch). ?

I would like to see the various types defined as in, isolating disconnects, load break, load make, fused, magnetizing load make / load break switch, double break ...

With the incursion of European devices into the North American markets and their continued dominance into the power distribution and transmission space with the likes of ABB, Siemens and Schneider, the terminologies of disconnector, isolator are being used more and more. IEEE may now be behind the eight ball.

Thoughts ?

Thanks

 

[ScottyUK]

There's the International Electrotechnical Vocabulary IEC 60050 in about a million separately-billable parts, and there's IEC 62271 which deals with HV primary plant. For metal-enclosed gear try IEC 60298.

Hope this helps - have you got deep pockets?


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If we learn from our mistakes I'm getting a great education!

 

[k0412d]

Hello,

As Scotty said, I would go for the International Electrotechnical Vocabulary (IEV) IEC 60050

Here below is the link for the online version of the IEV (aka Electropedia) :

http://www.electropedia.org/

k0412d.

 

[collies99]

Thanks to all, I ended up writing this:

Short form definition:
Switch:
A mechanical device that is capable of making, carrying, and breaking currents under normal circuit conditions. A switch may operate in an overload condition and under short circuit conditions. When closed, switches are rated to operate at the continuous current without overheating.

Disconnect:
A mechanical switching device when operated in the OPEN position must provide enough insulation to isolate the circuit electrically.

Disconnect switch:
A mechanical disconnecting mean when operated in the open position satisfies the isolating requirements specified for a disconnect and provide a visible break for confirmation.

Fused combination unit:
A combination of a mechanical switching device with one or more fuses assembled as a composite unit

Fused disconnect switch:
A mechanical disconnecting mean with fuses installed in series with one or more of its poles.

Fuse switch:
A switch in which a fuse link or fuse carrier with a fuse link forms the disconnecting mean.

Long form description:
Switch:
A mechanical device that can make or break power electrical ower in a circuit. A switch consists of contact(s) mounted on an insulating structure and arranged so that they can be moved into and out of contact with each other by a suitable operating mechanism.
The term switch is used to describe devices intended to operate when the circuit is energized, de-energized, under loaded or during unloaded operating conditions. This is a stark contrast to the circuit breaker which has one of its primary functions to interruption short-circuit currents. Although there are hundreds of types of electric switches, their application can be broadly classified into two major categories as an isolating disconnect with or without load making or load breaking capability. Disconnect are not designed to interrupt fault current, that duties has been reserved to the fuse and the circuit breaker. Disconnect do have fault current making ability as it can be switched onto a fault.

Disconnect Switch
A disconnect switch is a mechanical device used to change connection in a circuit or isolate a circuit from its source of power. An opened disconnect switch provides visible confirmation that the circuit have been opened. When all source of energy have been isolated, safety grounds can be attached to the de-energized equipment for workers’ protection. Switches can be equipped with grounding blades to perform the safety grounding function.
Disconnect switch are designed to continuously carry load currents and can momentarily carry short circuit currents until the associated protective devices have operated and trip the respective circuit breaker(s).
Disconnect switches are relatively slow-speed operating devices and are not designed for arc interruption. They are designed for no load switching, opening or closing circuits where negligible currents are made or interrupted, or where there is no significant voltage across the open terminals of the switch.
Disconnect switches can be used for bus sectionalizing, to by-pass breakers and equipment for maintenance / isolation. Interlocking hardware is required to prevent operation under load until rated load break devices have been operated.

Switch design:
Disconnect switch can be designed for vertical or horizontal operation and operates as a three pole device. Some design features are:
Vertical break
Double break
V switches
Center-break
Hook stick
Vertical reach
Grounding

Load Break Switch:
A load break switch is a disconnect switch that has been designed to provide making or breaking of normal load currents.

This is accomplished by the addition of hardware that increases the operating speed of the switch and incorporating arc interrupting equipment. Load switching capability can also be attain with the addition of arcing horns and whips. These switches are used to de-energize or energize a circuit that requires limited amount of magnetic or capacitive currents such as transformers exciting currents or cable charging currents.

In medium-voltage applications the most popular interrupter is the air magnetic type where the arc is driven into the arc chute by blow out coils. Blow out coils produce a magnetic generated by the arc current itself.

Load break switch are able to perform making operations under short circuit conditions, accidents do happen.