Power Switching Devices

Watlow has manufactured solid state power controllers for over forty years. Watlow’s POWER SERIES™ is a microprocessor-based product that features application flexibility unmatched by any other silicon controlled rectifier (SCR) power and solid state controller on the market today. Watlow’s POWER SERIES solid state controllers include single- and three-phase models from 65 to 250 amperes. Field configurable phase-angle or zero-cross firing improves application flexibility on-site where needed. 50/60Hz independent operation allows utilization almost everywhere in the world without special calibration considerations. Serial communication via Modbus® RTU allows setup and monitoring of load status from a computer station or control room. On-board semiconductor fusing improves reliability by protecting the SCRs from heater short circuits. Plus, on-board heater bakeout and control diagnostics can help eliminate initial start up problems. All these benefits are in a touch-safe package that can be quickly and easily mounted in a control cabinet. Watlow’s POWER SERIES solid state controllers are UL® listed and C-UL® recognized, ensuring that they meet world safety and operational standards.

The QPAC modular controller from Watlow is a modular silicon controlled rectifier (SCR) power controller with plug-in features for flexibility. Bases are rated from 150 to 1000 amperes in one-phase, three-phase, two leg and three-phase, three leg configurations. A variety of transformers from 120 to 575VAC, along with 50/60Hz operation, enable the QPAC modular controller to operate in applications anywhere. Plug-in control cards set the QPAC’s SCR firing modes: solid state contactor, burst firing (zero cross) or phase-angle models and are available with a wide variety of options. High speed fuses are included to protect the SCR modular controller from short circuit currents. 200KA short circuit current rating (SCCR) prevents arc flash.

The E-SAFE® II hybrid power switch provides reliable and accurate power switching up to 35 amperes at 158°F (70°C). This mercury-free product is specifically designed to operate in the higher ambient temperatures of foodservice applications. The use of mercury in relays is being eliminated by regulations in the United States and around the world. The E-SAFE II is the best choice for replacing mercury relay switches and the best performing product at the most economical price. Because of the product’s unique design, there is no need to purchase costly heat sinks used with traditional solid state relays (SSRs). In addition, since this is a three-phase device, there is no need to wire multiple command signals. With a switching life of millions of cycles and an ambient rating of 158°F (70°C), with no heat sink required, this product is superior to typical SSRs. The E-SAFE II hybrid power switch provides foodservice operators with longer contact life and higher performance than typical mechanical contactors used in equipment. By using Watlow’s patent NO-ARC technology, the E-SAFE II can switch millions of cycles to increase the life of the product with reduced noise and increased temperature accuracy. E-SAFE II’s inherent ability to operate at fast cycle times make it an ideal complimentary product for a time, proportional, integral derivative (PID)controller. E-SAFE II is mercury free, RoHS compliant by design, CE approved and C-UL®/UL® recognized. The reliability of the product is protected by a two-year warranty

The SERIES CZR solid state relay provides a low-cost, highly-compact and versatile solid state option for controlling electric heat. With DIN-rail and back panel mounting standard on every controller, the CZR solid state relay allows for simple and quick installation. The extensive capabilities of the SERIES CZR include single-phase, 18 to 42 ampere zero-cross switching up to 600VAC (see output rating curve). It’s unique integrated design removes the guess work associated with selecting a proper heat sink and precise terminations for the application. This solid state relay controller holds many agency certifications and is ideal for applications that require UL®, CSA and CE approvals. The SERIES CZR is available in VAC/VDC input contactor versions and all configurations are model number dependent and factory selectable. The SERIES CZR solid state relay is protected by a two-year warranty.

Watlow solid state relays (SSR) offer many of the advantages of solid state power controllers, but at a lower cost. Watlow’s extensive knowledge in power controller design led to the development of a special fast cycle input card that enables a solid state relay to operate from a standard 4-20mA instrumentation command signal. Test results show that zero-cross solid state relays in combination with the fast cycle card promote better temperature control and longer heater life than slow cycle relays. Through a time proportional cycle rate of 1⁄10 of a second, heater life will be extended. Both low and high voltage solid state relays are available from 24 to 660VAC. All ac output models include back-to-back silicon controlled rectifiers (SCRs) for a more rugged design than the traditional triac-based solid state relay. The internal design allows it to tolerate high currents and harsh electrical environments of heavy industry. Watlow also offers a switched VDC model for dc heating applications. Watlow provides all of the components necessary for trouble-free operation. This includes two standard convenience items: a thermal foil to ensure proper thermal transfer from the relay to the heat sink and belleville washers to ensure that the relay is mounted with sufficient pressure to enable good heat transfer. Matched semiconductor fuses and heat sinks are available to complete the power switching package.