Hello all,
I would like to ask you if you could please help me out with the design of a 10V surge protection box.
This circuit is meant to maintain voltage at 10V during a flashover episode. The voltage is supplied by a high voltage transformer and a main circuit breaker interrupts current at 9A.
As I am measuring current on an insulating surface and drive the signal to an oscilloscope and a measurent PCI card with +/- 10V input voltage, it is essential I maintain this voltage at an event of a flashover (high current arc).
The circuit we designed is based on a 2 level protection consisting of back to back ziener and shottky diodes (Please check the attached).
Four back to back Ziener diodes, 20W, 10V (A) and another four back to back ziener (C) and Schottky diodes (d) 9.1 V, are clamping voltage as soon voltage across the measurement resistor 1.5kOhms (B) exceeds 9.1 V or 10V if the schottkys fail. I tried it and it has worked fine. But at the 3rd flashover, the 22 Ohms,10W resistor (E) got ''fried'' as the fault current went throught it during flashover.
Could you please suggest another component that can withstand such a thermal stress during flashover?
I know that there might be other suggestion on the principle of desing but I am not able to radically redesign the circuit.
Your help will be very appreciated! Cheers guys!
PS: all resistors are 10W rated and the currents I measure before flashover dont pose a problem as they are a few milliamps ( peaks of 8mA worst case)
I would like to ask you if you could please help me out with the design of a 10V surge protection box.
This circuit is meant to maintain voltage at 10V during a flashover episode. The voltage is supplied by a high voltage transformer and a main circuit breaker interrupts current at 9A.
As I am measuring current on an insulating surface and drive the signal to an oscilloscope and a measurent PCI card with +/- 10V input voltage, it is essential I maintain this voltage at an event of a flashover (high current arc).
The circuit we designed is based on a 2 level protection consisting of back to back ziener and shottky diodes (Please check the attached).
Four back to back Ziener diodes, 20W, 10V (A) and another four back to back ziener (C) and Schottky diodes (d) 9.1 V, are clamping voltage as soon voltage across the measurement resistor 1.5kOhms (B) exceeds 9.1 V or 10V if the schottkys fail. I tried it and it has worked fine. But at the 3rd flashover, the 22 Ohms,10W resistor (E) got ''fried'' as the fault current went throught it during flashover.
Could you please suggest another component that can withstand such a thermal stress during flashover?
Your help will be very appreciated! Cheers guys!
PS: all resistors are 10W rated and the currents I measure before flashover dont pose a problem as they are a few milliamps ( peaks of 8mA worst case)