Voltage Clipping Device


Thread Starter


Have a device with a 24VDC power connector. Back voltage >50VDC is getting to the device from other units in the system and burning the circuit card. I am looking for a voltage clipping device or circuit that will clip any voltage >24VDC in this supply line to 24VDC. Any ideas? This is on a ship.
Last year I did project using small SilverMax servo motors (24V/50W). The company name is QuickControl and they are located in California.
To protect motors they have external device (reactor box of some sort) that clips excess voltage to protect electronics built in their
compact motors (full blown controller with amplifier...).

Alan Rimmington

I would start with a diode across the 24v eg IN4001 (cathode to +) to kill back emf and a varistor rated at say 27v. The varistor acts as a short circuit to voltages higher than its rating. Zenner diodes may also help but the rating will need carefull thought, again these act as short circuits to voltages above rating. Any good electronics dealer should be able to give advice on suitable components.

gerald beaudoin

Sounds like there are some good sources of voltage spikes on the distribution network. I would go after the sources and put reverse diodes across all the possible inductive DC sources rather than just protect some of the sensitive devices. For sure if you protect the sensitive device today, there will be another tomorrow. Go for the source of the problem! I have found MOV's to be very useful at protecting the input. Good to put a fuse in series with the input
followed by the MOV; that way if the MOV fails (usually short) it will blow the fuse.

Good Luck
Gerald Beaudoin

Johan Bengtsson

Not fully understanding your problem I would suggest locking at a properly sized zenerdiode or similar device This will short ciruit anything above the given voltage and that have to be somewhat more than the "normal" 24V and less than the voltage making any damage.

Note the zener will emit a lot of heat if you feed it with a high current, this will have to be calculated for and possibly a proper heatsink applied.

Depending on your actual problem this might or might not solve it so a better description might be needed.

/Johan Bengtsson

P&L, Innovation in training
Box 252, S-281 23 H{ssleholm SWEDEN
Tel: +46 451 49 460, Fax: +46 451 89 833
E-mail: [email protected]
Internet: http://www.pol.se/

Hakan Ozevin

Try to use very cheap components:
RC circuit in parallel to a 24 V varistor in parallel to a 24 V Zener diode (series resistor of course and transistor if necessary). The RC+varistor circuit is for transients, and zener diode is for long term regulation.

This is the simple solution if the problem is coming from the supply, however somtimes the problem is arousing from a floating supply, i.e. voltage differences between the neutral and the ground. Be careful. I am not sure about the grounding principle in a ship.

Hakan Ozevin