Introduction

The NARC (N(o) ARC) circuit is designed as an add-on to relay contacts which can be subjected to damage by switching heavy current and/or inductive loads.

The circuit needs no interfacing and does not consume power from the circuit to which it is connected. It functions by monitoring the rate of voltage change as contacts open or during the 'contact bounce' of closing. When potentially damaging levels are detected a triac device switches on to quench any arc that might form.

Tests have shown that, even with a highly inductive load, the contact life approaches the mechanical life of the relay mechanism. An additional cost saving is conferred as ordinary gold/silver contact material may be used.

Use of the circuit

Where Gorton Electronics manufacture products there is no licensing fee for using the patented circuit. For other manufacturers wishing to use the technology, Gorton Electronics will negotiate both blanket licensing agreements and royalty agreements.

Conclusion

The NARC circuit confers significant advantages when used in switching circuits. In that inter-contact arcing is virtually eliminated, the operational life of contacts can approach that of their mechanical life.

The NARC circuit does not need to be changed to suit different loads. The only stipulation is that the arc quenching triac is able to handle the maximum load requirement which should be the same as the contact which it is protecting.

An additional bonus is that the NARC circuit will make the mandatory European Directive on Electromagnetic Compatibility easier to achieve in equipment as it is often the switching arc that leads to unacceptable levels of spurious signal radiation and conduction. Usually, it is necessary to employ shielding and/or expensive filtering.

The employment of the NARC circuit can, therefore, result in the lowering of equipment cost and the lengthening of service life.