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# HVDC Warning Indicator

## HVDC Warning Indicator

(OP)
I am looking for a way to indicate danger in a HVDC (80-1,000 VDC) junction module when dangerous voltage is present even when the machine is shut down. The system I am working with can have stored voltage of up to 1,000 VDC. I am thinking that I could use an LED that is connected to the HVDC through a current limiting resistor that would stay on down to about 40-80 V and then go off.

My constraints in order of importance are 1. space efficient, 2. simple, 3. cost effective.

So far for this I have used a DC/DC Converter to drop the 80-1,000 VDC down to a regulated 12 VDC to power a TruMeter Voltmeter. It has been working well, however, this method meets none of my constraints.

Thank you in advance for any suggestions!

### RE: HVDC Warning Indicator

An LED would require 5 to 10mA of current for typical brightness. Means you will need minimum a 5 to 10W power resistor. Doesn't have to be an LED. You could use a good old-fashion neon bulb. They will light well with 500uA current. So you would need more like two 1 Meg 1/2W resistors in series. Once the 1000V excites the neon, the current will flow, and the bulb will remain ON as the voltage drops.

You could begin experimenting with a typical 115VAC neon pilot lamp. These usually contain internally a 220K to 270K resistor in series. Just add more resistors in series. A single typical axial 1/2 resistor should not be used at more than 500V which is why I suggest several in series.

### RE: HVDC Warning Indicator

(OP)
Thank you Comcokid! I am going to order some components and try bread-boarding this.

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