Improved thermal characteristics from SS relays

Edited by the Engineeringtalk editorial team Jan 22, 2001

Crouzet has announced a revolutionary new generation of solid state relays that offer EMC compliance and improved thermal characteristics inside the industry standard hockey puck package.

Crouzet has announced a revolutionary new generation of solid state relays that offer EMC compliance and improved thermal characteristics inside the industry standard 'hockey puck' package.

A new range of EMC compliant, surface mounting, optically coupled, solid state relays with a choice of covered or open terminals.

These relays feature Direct Copper Bonded technology, which with the unique internal design dramatically reduces the size of heat sink required and extends the unit life by up to 10 times that of a conventional unit.

These relays have a sealed construction, with N/O Thyristor output circuits, having no moving parts, a long life and high reliability.

The switching is silent and is not affected by vibration.

Zero Volt switching can be used for switching single phase resistive loads or motors where the power factor is greater than 0.8 and random switching versions for Inductive Loads (motors) with a power factor less than 0.8 are offered.

By providing EMC compliant SSRs at the same or lower cost as non-compliant competing devices, Crouzet not only saves engineers and designers the cost of the components, but also saves a lot of wiring, time and trouble.

Also included in the standard price is a choice of IP20 rated safety cover or an IP00 uncovered (topless) versions.

Both versions have a diagnostic LED that lights when the SSR is 'on'.

Available in 10, 25, 50, 75, 100 and 125A ratings, with a choice of 280V or 660V AC duty, the GN Series is housed in a 60 by 45mm double hole fixing hockey puck, 32mm high.

GN Series inputs accept 4-32V DC regulated at 14mA maximum to suit PLC outputs or 5V logic signals and are isolated 4000V from the output circuit.

Higher voltage AC and DC input versions are also available.

Connections are made with easy to use self lifting Pozidrive clamp terminals designed to accept one or two wires up to 2.5mm2, which are protected by the safety cover on the IP20 versions.

Temperature rating is -20 to +80 oC.

Legislation now requires all electrical equipment to conform to the so called EMC directive, and to carry a CE mark to demonstrate compliance.

This requires devices emitting electro-magnetic interference (EMI) do so at levels well below those that cause interference to devices susceptible to EMI, so ensuring Electro Magnetic Compatibility or EMC.

Because SSRs typically switch significant amounts of power, the electrical systems they form part of are prime sources of EMI and suppression components need to be fitted to prevent EMI from being emitted.

Most SSR makers take the view that since the final product is the designer/makers responsibility, they can leave the designer to specify, source and fit the appropriate EMI suppression devices.

While this approach is legally correct, Crouzet feels that it is unhelpful and prefers to provide a solution by fitting suppression components inside the SSRs to save time and cost for the designer.

EMC Class A compliance also requires devices to be immune to specified levels of EMI from other sources and the Crouzet GN Series is fitted with suppression components at the input as well as the output, to ensure this condition is met.

Of course, since Crouzet is not able to predict every application of their components, it is not possible to guarantee that the fitted suppression components alone will ensure compliance.

Every manufacturer should test his finished product.

However, Crouzet's experience as one of the world's biggest SSR makers is that the components fitted will be adequate for the vast majority of applications and so there should be no further work to do apart from checking for compliance at the design stage.