Accessories for SSRs & Drives
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Heatsinks, Fuses, Transformers
To compliment our range of solid state relays and drives,
we offer a wide range of specialised accessories such as heatsinks, ultra-rapid fuses & fuseholders, fan kits, silicone heat transfer paste and transformers..
contact us to discuss your requirements.
FUSE PROTECTION
Suitable fuse protection is a recommended precaution when using SSRs. Circuit breakers and similar overload protection devices are too slow to prevent damage to SSRs when short circuits occur.
For this purpose ultra-rapid fuses are needed. It is common practice to install DIN-rail mounted fuse holders, making replacement of fuses easy.
HEAT SINKS
SSRs dissipate power proportional to the load current. When the load current exceeds 4A, heat sinking becomes essential. SSRs should not be mounted directly onto the backing plate of instrument panels as this often leads to overheating. It is also advisable to study the current versus-temperature derating curves when selecting heatsinks.
We recommend to put thermal strips onto heatsinks, changing colour when the rated temperature is exceeded. This makes it possible to detect overheating.
VENTILATION
Because Solid State Relays dissipate heat, adequate ventilation needs to be provided in panels and enclosures containing SSRs. If a number of SSRs and other heat generating components are mounted in a panel, it may be necessary to provide forced ventilation. Care should be taken to ensure good airflow over the heatsinks.
Therefore the positioning of air vents is important. Obstructions and blind corners should be avoided. When using fans we recommend that the fans blow out rather than suck in. Inlet vents should be spread over a big area, preferably on the underside of the panel. This prevents plastic foil or paper from blocking the suction inlet. Air vents on top of panels should be avoided because somebody may innocently place an obstruction there.
OVERVOLTAGE
On three-phase loads it is advisable to use SSRs with a rating of 400-480V, even if a neutral is connected. When the neutral conductor fails or is absent, the voltage perhaps may exceed 250V and reach 400V or more. SSRs with a voltage rating of 250V.
Should the stated point be outside the working area, it is necessary to equip the heatsink with a fan and a safety thermostat.
N.B. The operating point has not to be outside the delimited area.
- DIS908/910 heatsinks are suitable for three phase solid state relays of RZ series
- Controlled three-phase effective current refers to the used line current of three phase load.
- Heatsinks used with a cooling fan should be equipped with safety thermostat, so that the solid state relay can be switched off in case of fan failure.
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