Hello friends. I am designing a test fixture that will be used for dielectric strength and insulation resistance testing. It will be used for multiple units used on commercial aircraft. My plan is to use 35 toggle switches that will be used to select which wires are in circuit for DS and IR testing. The voltages typically used for these tests will be 1.2KVAC and 500VDC. I've been looking at the S303 SPDT switch from NKK Switches but I'm uncertain as to how their switch voltage ratings will apply in my application. The switches are rated for 15A@125VAC, 6A@250VAC, and 20A@30VDC. As you know, the current in view when doing DS and IR testing is very small, no higher than 5mA.

Will the application of 1.2KVAC and 500VDC from a Hi-Pot tester destroy these switches?

Thanks for your input.

Mike

 

Hello,

What are IR and DS testing?
There is a great chance of arcing when you use a switch on a higher voltage than rated.

Bertus

 

IR is insulation resistance testing. DS is dielectric strength testing. Arcing is one of my concerns and that's why I am looking for answers as to what those voltage ratings on the switches actually mean. I was trying to extrapolate the numbers using Ohm's law and am actually still toying with that but I want to make sure I have the right information on the switches before I spend the money for all the switches and build it only to find out it's not going to work. I hate when that happens.

 

When using AC switches for DC, you have to “derate” the specifications. Take a peek at this thread.

 

You cannot use the switches you indicate, they will arc over. You need to get high voltage relays like this:
https://www.spselectronic.com/us/products/details-us/relay-rl-21-1/

Or some other similar product. Use your switches and a power supply to control the the relays.

 

Hello friends. I am designing a test fixture that will be used for dielectric strength and insulation resistance testing. It will be used for multiple units used on commercial aircraft. My plan is to use 35 toggle switches that will be used to select which wires are in circuit for DS and IR testing. The voltages typically used for these tests will be 1.2KVAC and 500VDC. I've been looking at the S303 SPDT switch from NKK Switches but I'm uncertain as to how their switch voltage ratings will apply in my application. The switches are rated for 15A@125VAC, 6A@250VAC, and 20A@30VDC. As you know, the current in view when doing DS and IR testing is very small, no higher than 5mA.

Will the application of 1.2KVAC and 500VDC from a Hi-Pot tester destroy these switches?

Thanks for your input.

Mike

You'll have to look at the insulation breakdown characteristics of each component used to route the Hi-Pot test voltage to the DUT(including any wires). The switches should have a rating specified on their data sheet.
Beyond the datasheets, the only really way to know is to test the fixture with the selected components.

eT ​

 

You cannot apply 1200 VAC to a 250 VAC switch and expect a good outcome!

The high voltage relays have the contacts sealed in an inert gas. This will extinguish the arc that occurs when the contacts open. Using a switch in air will ionize the air and may have a sustained arc. It can also burn the plastic insulation and cause a conductive track between the contacts.

Always put safety first and using under rated switches is not safe!