PLC system spare parts supply 3BSE042238R2

PLC system spare parts supply 3BSE042238R2

PLC system spare parts supply 3BSE042238R2

In most cases, the ambient temperature for the operator panel is significantly higher than the device cabinet’s ambient temperature. If the cabinet is tall and there are a number of heat-generating devices, the temperature at the top of the cabinet will be considerably higher than the theoretical temperature increase that would be expected.

All electronics are sensitive to heat. The lifespan of an electrolytic capacitor is cut in half with an 8-10 °C increase in temperature.

A 15-20 °C temperature increase results in a quarter of the lifespan etc. Rittal has a good program for estimating the anticipated average temperature in the cabinet as well as a large program for controlling the temperature in the device cabinet. An enamel-coated steel cabinet has a radiant heat value of 5.5 W/m2 and °C.

Installing a fan inside the cabinet will even out the temperature, while moving air provides considerably better cooling than still air. A suitable fan is a 120 x 120 mm axial fan, available in 24 V DC, 115 and 230 V AC. Install the fan so that it sits in the cooler area and will blow cold air against the operator panel. If the fan is mounted at the top and sucks air upwards, the fan’s ambient temperature will be higher = shorter lifespan.

A good fan with a ball-bearing mounting has an expected lifespan of at least 40,000 hours (not a guaranteed lifespan) at 40 °C. This corresponds to at least 4 years of continuous use. If a thermostat is installed, the fan only needs to come on when needed. Large graphic terminals draw only one fifth of the current when the background lighting is off. The loss effect drops from e.g. 25 W to only 5 W. The operator panel’s loss effect = supply voltage x current. Virtually no power goes to external users and no loss effects due to inputs.