Disconnect switch rated 1000V 4

[Nick Smith]

Hi. I am new to Electrical Design (in fact this is the first project). My load is rated 1000V /800A . The main disconnecting means is a vacuum contactor 4KV ( overkill I know but not my decision). My manager asked for disconnecting switch and I have hard time to find something at 1000V ( everything available stops at 690V and after that it jumps to MV). Does anybody have a suggestion for this? Thank you in advance

 

[jghrist]

Why not use 4kV? I don't know what you mean by "after that it jumps to MV"
1000V is an odd voltage. What load equipment is rated at 1000V? What is the operating voltage?

 

[che12345]

Dear Mr Nick Smith (Electrical)(OP)21 Feb 23 21:47
"....#1. My load is rated 1000V/800A . #2. The main disconnecting means is a vacuum contactor 4KV ( overkill I know but not my decision). #3. My manager asked for disconnecting switch and I have hard time to find something at 1000V ( everything available stops at 690V and after that it jumps to MV)....."
1. What system are you working on rated at 1000V, which is a non-standard voltage? A very bad selection. That is way you are having difficulties to source for the right LV equipment, otherwise would go into the MV voltage gears, which are very much more expensive.
2. Attention: The main disconnecting means is a vacuum contactor 4KV .... is NOT allowed to be used as an disconnector!
3. In Europe, there are numerous ACB manufacturers that include 1000V/800A AC Breaker and Disconnector in their standard production program. These products rated at 1000V ac are very much lower cost than a MV gear.
4. Note: These Breakers open clearance would fulfill the Disconnector requirements/standards.
Che Kuan Yau (Singapore)

 

[bacon4life]

Where is your project located? This forum has folks from all over the world.

At around 1000 volts there are new kinds of considerations for the design of electrical equipment. For example, at 600 volts a power cable consists of just a conductor surrounded by insulation. Above 1000 volts, there is an additional grounded shield on the outside of the cable. The grounded shield prevents capacitive coupling to adjacent objects and it prevents concentrations of electrical stress that can lead to partial discharge damage.

Using 1000 volts seems like the worst of having to design with partial discharge in mind, but still needing almost as much conductor cross section as at lower voltages.

 

[che12345]

@ Mr bacon4life (Electrical)22 Feb 23 01:05
"....#1. Where is your project located? This forum has folks from all over the world. #2. At around 1000 volts there are new kinds of considerations for the design of electrical equipment. For example, at 600 volts a power cable consists of just a conductor surrounded by insulation. Above 1000 volts, there is an additional..."
1. In Europe where IEC is the norm, LV covers up to 1000V ac and 1500V dc. All equipments up to 1000V ac and 1500V dc are considered as LV; covered by the same standard (e.g. IEC 60947-x ...) for breakers, contactors, disconnectors etc...
1.1 Note: In most cases a 1000V ac Breaker /disconnector is actually the same 690V ac breaker/disconnector but labelled with lower I[sub]cu [/sub], i[sub]cs[/sub], I[sub]cw[/sub] etc.... Therefore physically interchangeable. Attention: But with lower ratings.
2. IEC 60947-x covers up to 1000V ac and 1500V dc. Therefore, Breakers, Disconnectors, Contactors etc... are covered by this single IEC standard.
Che Kuan Yau (Singapore)

 

[LionelHutz]

Look at Socomec.

 

[Nick Smith]

@ che12345 , unfortunately not my choice . This is expected voltage on a power cell which are cascaded to achieve 14KV. The vacuum contactor I use is "free" plus it suits to the harsh regime this design is intended for. The project is located in Canada .

 

[bacon4life]

By cascaded, do you mean you will have 14 of these in series? Is there any chance you could end up with 14 kV across the disconnect when one switch is open and the other 13 are closed? In addition to withstanding voltage across the switch, switches also need to be rated to withstand the phase-to-ground voltages.

 

[jraef]

AC or DC? Makes a HUGE difference because switching DC is very difficult. You cannot assume that a disconnect (or contactor) will handle 1000VDC just because it can handle 1000VAC. You must look for specific ratings.

1000VDC is a more common occurrence in Solar PV systems now, so there are products available for that, but you have to be looking in the right places. Socomec as previously mentioned is one that I believe has 1000VDC solar PV disconnects, ABB is likely another. In those cases you can attain 1000VDC ratings using 4 pole circuit breakers or disconnects by looping two sets of contacts in series for each DC pole. I’ve done this with ABB breakers (10+ years ago so I don’t know if they still offer that) before finding out that Socomec had them available as disconnects for a lot less.

https://www.socomec.com/range-load-...en.html?product=/sirco-pv-iec-60947-3_en.html

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