Feedback from a large customer of unitemp revealed that Gefran’s power controllers made a substantial difference in the fabrication of their electrical kilns. Unitemp recently supplied them with Gefran’s Wattcor Solid State power controllers. The Wattcor W212 and W211 include a wide range of highly reliable solid state power controllers with "zero crossing" switching for resistive loads with current ratings up to 600A and 660Vac nominal voltages.
Compared to thyristor and contactor switching devices, there are a number of distinct advantages of the Wattcor SSRs which has made these units popular in furnace type applications as in the above mentioned case:
1. Wattcor is designed without any moving parts - all solid state. It can, therefore, be used in dusty and rough environments whereas contactors would show reduced lifetime.
2. Wattcor is zero-switching: this means that the on/off switching of current happens at the zero point of the sinewave. This is the ideal switching point at which the generation of electrical noise is minimized. Thyristor type units switch along the sine wave, creating high levels of harmonics and, therefore, high electrical noise which interferes with other equipment in the area (as this noise is fed back into the system).
3. Cooling requirement is minimized: as they are switching at the zero point, the heat generated by the components is considerably less. This allows more compact construction with less cabinet real estate and reduced expenditure on cooling.
4. Wattcor is available in high current ratings as well as high switching voltage: units rated up to 600Aac and 660Vac are available. These models provide robust switching in areas that may experience supply that does not comply with the normal Eskom standards.
5. Wattcors are designed to operate reliably at high ambient temperatures: Large heatsinks allow the units to operate at full load up to 50°C ambient temperatures before they need to be derated. This provides additional robustness in rough industrial applications.
6. Various inputs allow easy control from PLC: the control input on the W212 model can be set to standard industrial signals like 4-20mA, 0-10Vdc, 0-5Vc, 0-20mA or potentiometer input.
Unitemp supplies the widest range of Gefran products including controllers, SSR’s, sensors, transducers and indicators.
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