High Pressure Contact switch

[Grouch1980]

Hi,
Can someone please explain how a high pressure contact switch works? and why / how is it better than a bolted pressure switch?

Thanks!

 

[LarryFine]

Can you provide an example of each?

 

[Grouch1980]

I wish I had that! I don't have examples, and I can't find anything on google. Maybe I can add this... a 1600 amp bolted pressure service switch in a switchboard. How does a 1600 amp high pressure contact switch differ in operation?

 

[Grouch1980]

This is all I could find: A sub-category is evaluated for fused switchboards that include the Bolted Pressure Switch (BPS) versus the High Pressure Contact (HPC) switch. Though both are essentially the same price, the HPC switch is about 16% smaller for these cases. Each is classified as a Fused Power Circuit Device and listed under UL977, but only the HPC incorporates an over-center toggle mechanism with high-energy springs and silver-tungsten carbide alloy butt-type contacts. This construction provides it with higher short-time ratings and faster operating speeds (under 3 cycles!), placing it in a breaker-class of reliability.

Is this how a high pressure contact switch works? Can anyone provide a picture of the inside of an HPC switch? I can't picture what they wrote.

 

[jim dungar]

Hi,
Can someone please explain how a high pressure contact switch works? and why / how is it better than a bolted pressure switch?

Thanks!

A high pressure contact switch looks like breaker contacts, two surfaces that but against each other and are held in place by a mechanism that provides a high amount of pressure. Look for information on GE HPV.

Bolted contact switches look like standard knife switches with the movable contact being in two pieces that close on either side of the stationary contact. As the switch finishes closing the mechanism continues to move thereby tightening a set of bolts in the movable blade. This tightening process effectively bolts the movable contact to both the line and load side stationary contacts. Look for Pringle, Bolt-loc, and Boltswitch.


Based on the fact that only one major manufacturer makes a true high pressure switch, while several make bolted pressure ones, I don't think they are inherently better. However they have a lot in common with power circuit breakers, so I expect to see more of them offered in order to comply with the requirement for Energy Reduction Method on fusible switches.

 

[Grouch1980]

A high pressure contact switch looks like breaker contacts, two surfaces that but against each other and are held in place by a mechanism that provides a high amount of pressure. Look for information on GE HPV.

Bolted contact switches look like standard knife switches with the movable contact being in two pieces that close on either side of the stationary contact. As the switch finishes closing the mechanism continues to move thereby tightening a set of bolts in the movable blade. This tightening process effectively bolts the movable contact to both the line and load side stationary contacts. Look for Pringle, Bolt-loc, and Boltswitch.


Based on the fact that only one major manufacturer makes a true high pressure switch, while several make bolted pressure ones, I don't think they are inherently better. However they have a lot in common with power circuit breakers, so I expect to see more of them offered in order to comply with the requirement for Energy Reduction Method on fusible switches.

Thanks!! are either, BPS or HPC, required by the NEC? or only optional?

 

[jim dungar]

Thanks!! are either, BPS or HPC, required by the NEC? or only optional?

I am not aware of more than a handful of 600V switches between 800A and 1200A that are not one of these styles. Well at least not ones built in the last 45 years.
At 1600A and larger I don't think there is any other choice.

 

[jim dungar]

Look for information on GE HPV.

Oops - Make that GE HPC.

 

[ron]

In some areas, you would think bolted pressure switches are in the local code, just because they are all over the place, but it is just because it is easy to get them at "high" ampacities and high short current ratings (they are fused) and cheaper than breakers for the equivalent ratings.
GE's attempt at making a hybrid type device that would be proprietary and compete with the bolted pressure switch is the HPC. GE/ABB will tell you it is better. It is good, I have used many, but not better.

 

[bwat]

Can HPC and BPS ever be used in combination with protective relay for protection or is the contact only to be used for switching and the fuse provides all OCP?

 

[jim dungar]

Can HPC and BPS ever be used in combination with protective relay for protection or is the contact only to be used for switching and the fuse provides all OCP?

Yes.
Fuse provide high fault current clearing, but other levels can be handled by the contacts only.

 

[bwat]

Yes.
Fuse provide high fault current clearing, but other levels can be handled by the contacts only.

I'm curious, at what point is it impossible to distinguish between a breaker and a HPC then?

I'm trying to separate the marketing and trade terms vs the technical. Not exactly the same, but a similar example would be a large relay vs small contactor... I'm not aware of when one truly becomes the other. They're just coils and contacts with certain ratings.

 

[Jraef]

A "breaker" includes the protection systems as part of it, an HPC is for when you want fuses.

But an imprtant difference is that a Power Circuit Breaker (PCB) is designed to be serviced and rebuilt, an HPC is not, it is "maintenance free" which can also be interpreted as "throw away". They are required to interrupt at rated current 12 times, after that it's a craps shoot. So for all intents and purposes, you would only use an HPC on something that is NOT opened under load.on a regular basis.