Calculating DC Withstand Voltage on a Power Connector

Assuming the spec is 1800 vrms , the DC withstand would be about 2500 vdc.

You have plenty of safety margin.

That is the thing, it doesn't specify Vrms but AC which is a little different. Wouldn't the dielectric charactistics of the insulator come into play?

For example, another connector I found, had specifactions of 500VAC withstand voltage at 5amps and than states that the maximum DC contact voltage is 12Volts? So the solution can't be that simple. :)

please see IEC 60947-1 where u will get ur answer, normaly V ac = 1.41 V dc, so for 1 kv ac is equivalent to 1410 v dc,

please refere the standar, u will make it very clear for the same

regards

divyesh patel

IEC 60947-1 is $314 for a paper? To rich for my blood and I doubt my company would pay for that, just for interest's sake.

Ok, the arching makes sense why the VDC withstand voltage is less than the VAC and the current would play a big part of this. The application is a power plug being inserted into a socket, so arching would need to taken into consideration, but there is no actual switching done in the connector.

I'll have to grab a book on quantum physics to read this summer, seems that's the way electronics is heading...lol.

DC voltage is much harder to handle than AC because of the lack of zero crossing that extinguishes the coronas just before an arc is ignited. This becomes even more important in applications where the connector is exposed to dearth and humidity. Over time, the DC will ionises a track of dearth between the contacts and arc over. AC does this much less.

Below about 100VDC, the equivalent AC rating is often used but above this one must be very careful. The dc rating is quickly limited while the AC rating can increase.

" but there is no actual switching done in the connector."

Maybe I should have clarified that a little. When I referred to using the connector for switch duty, I merely meant connecting and disconnnecting under power. Not an actual switch in the connector.

Although, the Brits and Australians do have a good system of switches in their sockets. So you don't (thoeretically, at least) plug and unplug under power.

ok, thanks for clarifying because there are power connectors which have a mechanical switch inside. :)

We have to expect the customer will plug in wall outlet before the device so yes the connector will have switch duty, but in most cases the product would not be moved so the switch duty should be fairly light.

No problem.

Like I said earlier, 18.5V@3A? You could probably plug and unplug that connector (under power) all day long with no problems. My comment on switch duty really only applies at higher voltage and/or current levels. (ie tens to hundreds of amps and/or around a hundred volts and higher.)

Cheers

ianr is correct, 1.41xAC is a maximum. further derating must be done especially with an inductive load.

hi to all

i have gone through the answeres received from all, but connectors are only associated with continuous carring capacith, they are never been associated with its making and breaking capacity, yes but maximum carring capacity can be assigned to them, so with irrespective of rated operational voltage, connectors are more importantly rated by their rated insulation voltage perticularly at DC when AC rating is defined.

and if AC swtiching devices are intended to use at DC supply, they required to change its design because in DC breaking is more painfull for device, which depends on time constant of load, speed of opening of contact, contact tip and its material, distance between contact and laste but not least on arc chutes used.

so kindly refere IEC 60947-1, EN 60947-1 or CSA,IS or japaness standard specifies that DC = 1.41 * AC

regards

divyesh patel

X employee of ERDA (Switchgear), currently working in Bombardier Transportation India Ltd. (Test lab)