Watlow Solid State Relays (SSR)

Watlow solid state relays (SSR) offer many of the

advantages of solid state power controllers, yet at a

lower cost. Watlow’s extensive knowledge in power

controller design has led to the development of a special

fast cycle input card that enables a SSR to operate

from a standard 4-20mA instrumentation command

signal. Test results have shown that a zero cross SSR

in combination with the fast cycle card promotes better

temperature control and longer heater life than slow

cycle relays. Through a time proportional cycle rate of

one tenth of a second heater life will be extended.

Both low and high voltage models are available from

24 up to 530VAC. All ac output models include

back-to-back Silicon Controlled Rectifiers (SCRs) for a

more rugged design than the traditional triac based SSR.

The internal design allows it to handle high currents

and the harsh electrical environments of heavy industry.

Watlow also offers a switched VDC model for dc heating

applications.

Watlow can provide all 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

belville washers that ensure the relay is mounted with

sufficient pressure for good heat transfer. Matched

semiconductor fuses and heat sinks are available to

complete the power switching package.

Features and Benefits

Fast cycle card

• Increases heater life

• Optimizes temperature control

• Allows for higher watt density heaters

Zero cross firing

• Results in minimal electrical noise

Back-to-back SCR design

• Withstands harsh or hostile industrial environments

UL® recognized File #E151484 and #E73741

CSA certified up to 600VAC, File #LR700195

VDE 60950 License #40021401. File #1995500

up to 480VAC, CE - EN 60950 and RoHS

• Meets applications requiring agency approval