hv panel switches

Not a shock hazard, but make sure the switch can break that much DC. Most cheap toggles are rated for AC use, and might arc breaking hundreds of volts of DC.

John

Mark Jones schrieb:

Hello,

you should read the datasheet of the switches about the DC voltage.

Bye

Select the switch by reading the data sheets and find a unit that has ratings in excess of the voltage and current that you intend to switch. Equally important is that you select components that carry a safety agency listing of approval that is accepted in the countries where you expect to do business. If you also get your product safety agency listed they will likely kick back on any part of your design and/or component selections that do not meet the applicable safety standards.

I once bought my power supplies from a semi-custom vendor in NH. They sold a potted "brick" which produced a clean +/-15V from an AC input. Toggle switch, fuse, LED, the works. My clients couldn't get enough of them. Until one of them took a line shock by touching the bat of a toggle switch that had failed. This was a potted module, so the switch wasn't mounted to a grounded panel, so it's not quite the same situation that you have. Just keep in mind that switches can fail in a nasty way, so if you're switching dangerous voltages, either use a plastic bat or rocker, or make sure the metal bat is in contact with ground.

-Jim MacA.

They always break the DC at some point. Sometimes after 10sec of evil hissing, ozone smell and fire alarms blaring. Other times only after engine company 87 has shown up and cut power to the building :-)

Yes, that would be my main worry, that the toggle bat would short energized, but the panel would still be grounded, allowing for a nasty shock or burn to an unwary user!

Charlie

Or they're rated for 1/10th the DC than their AC rating.

If safety is a concern, find safety rated switches.

Excellent point.

John

You must be careful with DC voltage..

If you look at the ratings on switches, you'll find them rated in AC and DC volts. You'll also notice that DC voltage rated is lower.

THe problem is all about plasma! Making and breaking contacts generates an arc which has a composite of vaporized conductive material in a gasses form, this is know as plasma. Since this is vary conductive, in AC applied voltage the source to ignite this ends when it drops to 0 volts as it crosses over to the opposite polarity, this will extinguish the flame, since the plasma is being repelled outwards.

When DC is used, this drop in voltage does not happen and thus a steady supply of current is operating, breaking down the material of the contact surface, there by, generating more plasma to keep it going.

This only stops when the gap between the contacts become apart enough to where insufficient current can be generated to keep the process going.

Of course, by that time, a lot more material has been removed from the contacts, and at some point the contacts will be unusable.

Hence the reason why we have DC and AC fuses.

Jamie

Big rubber mallet and huge knife switch ;-) ...Jim Thompson