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The LOW NOISE SOLID-STATE RELAY produced by Root2 Ltd has been developed to fulfil the requirements of European Directive 2004/108/EC and the associated EMC Standards:

  • EN50081-1(1992) Generic emission standard, (Part 1)
  • EN50082-2(1995) Generic Immunity standard, (Part 2) Industrial
  • EN61000-3-2(1995) Mains Harmonic disturbance

These Standards set limits for the amount of RF noise that can be emitted and the immunity from RF noise for electrical apparatus within the countries of the European Community. [similar EMC regulation also applies within the USA and other developed countries].


The new harmonised Regulations for Electromagnetic Compatibility of equipment is set out in Directive 2004/108/EC and for the purposes of this Directive the following definitions will apply:

1. Equipment: any apparatus or fixed installation.

2. Apparatus: any finished appliance or combination thereof made commercially available as a single functional unit, intended for the end user, and liable to generate electromagnetic disturbance, or the performance of which is liable to be affected by such disturbance.

A component or sub-assembly intended for incorporation into an apparatus by the end user, which is liable to generate electromagnetic disturbance, or the performance of which is liable to be affected by such disturbance, is deemed to be an apparatus for the purpose of this directive.

Solid State relays certainly generate considerable levels of continuous R.F. noise and are also susceptible to electromagnetic disturbance from outside sources, therefore they fall within the requirements of the Regulation. The new Directive also states that manufacturers of these components must provide the end user with full technical information on methods of making the component EMC compliant, ie use of in-line EMC filters.

It should be noted that the Directive also applies to FIXED INSTALLATIONS which means that electrical switch boxes controlling building services at fixed locations are now included. Certainly the control of services and machinery such as lights, heating, HVAC, lifts, etc within a building or facility are just as problematic with regard to EMC as any single apparatus.

The ROOT2 solid state relay has been fully tested and certified as EMC compliant while operating with a 240vac 80amp load - the immunity test involved the introduction of 1KV pulses at the low voltage control circuit and immersion in high power RF signals within a sealed chamber. The new relay therefore represents a simple and cost-effective method of complying with the EMC directive while reducing electrical noise and improving immunity within all types of industrial and commercial apparatus.

In most cases the use of certified compliant SSR's will reduce the noise output of the whole apparatus to within the EMC limits or reduce the cost of additional filters considerably. Many manufacturers will be surprised to learn that solid state relays will probably be the single most significant generator of RF noise within the whole of their apparatus: a typical SSR operating with a 30amp load produces a continuous noise output of over 120db at 150KHz, (the EN55022 limit is 65db).

A new Product Specific EMC Standard for Machine Tools, EN50370 will be introduced in the Summer of 2004 and it is possible that changing over to low-noise SSR's could bring existing machinery within the EMC limits without expensive design changes.

The Root2 solid state relay is supplied in the same package as a standard SSR making it fully interchangeable with existing types. All Root2 Ltd relays are RoSH compliant (EC Directive 2002/95/EC)