Solid State Relays with AC or DC Control Inputs
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- Current Ratings to 100 Amps
- Multi-Million Cycle Life
- Compatible with Temperature Controllers
- Solid-State, SCR Design
- Zero Voltage Switching
- Control ac Lines to 660 Vac
- AC and DC Control Signal Models
- LED Input Status Indicator
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The Omega's SSRL series of solid state relays are used to control large resistance heaters in conjunction with temperature controllers. Solid state relays are SPST, normally open switching devices with no moving parts, capable of millions of cycles of operation. By applying a control signal, an SSR switches ON the ac load current, just as the moving contacts do on a mechanical contactor. Three-phase loads can be controlled using 2 or 3 SSR’s. Use 3 SSR’s for Y or star 3-phase loads using a neutral line. Two SSR’s will control “delta” loads with no neutral line. Three solid state relays are also used when there is no neutral load to provide redundancy and extra assurance of control.
'Switching' takes place at the zero voltage crossover point of the alternating current cycle. Because of this, no appreciable electrical noise is generated, making SSR’s ideal for environments where there are apparatuses susceptible to RFI.
Operating Temperature: -20 to 80°C (-5 to 175°F)
Storage Temperature:-40 to 80°C (-40 to 175°F)
Isolation: 4000 Vrms, input to output; 2500 Vrms input/output to ground
Capacitance: 8 pF, input to output (max)
Line Frequency Range: 47 to 63 Hz
Turn-On Time: 20 ms, ac; 05 cycle, dc
Turn-Off Time: 30 ms, ac; 05 cycle, dc
These SSR’s are of the twin SCR type, inherently more reliable and capable of higher overloads before failure than triacs. Heat is developed in a solid state relay due to the nominal voltage drop across the switching device. To dissipate the heat, an SSR must be mounted on a finned heat sink or aluminum plate. An SSR should be located where the ambient temperature is relatively low, since the current switching rating is lowered as the temperature increases. Another SSR characteristic is a small leakage current across the output when the relay is open. Because of this, a voltage will always exist on the load side of the device.
In comparing SSR’s with mechanical contactors, the SSR has a cycle life many times that of a comparably priced contactor. However, SSR’s are more prone to failure due to overload and improper initial wiring. Solid state relays can fail, contact closed, on overload circuits. It is essential that a properly rated, fast blowing I2T fuse be installed to protect the load circuit.
Finned heat sinks are anodized fabrications that come complete with tapped mounting holes and screws. See thermal rating curves and ordering instructions for proper selection.
All SSRL series relays come with a thermally conductive pad mounted on the baseplate. This will significantly improve the thermal conductivity between the heat sink and SSR baseplate. It is also suggested that 10-inch-pounds of torque be used on the SSR mounting screws.
Output Specifications for Vac and Vdc Input Models
Specifications 10 Amp 25 Amp 50 Amp 75 Amp 100 Amp Max On State Current 10 A 25 A 50 A 75 A 100 A Max On State Current 100 mA Max 1-Cycle Surge 150 A 300 A 750 A 1000 A 1200 A Max 1 sec Surge 30 A 75 A 150 A 225 A 300 A 12T (60 Hz), A2sec 416 937 2458 5000 6000
SSR240 Series Electrical Specifications
Input-Control Signal Output Model No. Type Control
(60 Sec. Max.)
90 to 280 Vac 90 Vac 10 Vac 10 mA 800 V SSRL240DC10
3 to 32 Vdc 3 Vdc 1 Vdc 14 mA 800 V SSRL660AC50
90 to 280 Vac 90 Vac 10 Vac 10 mA 1200 V SSRL660DC50
4 to 32 Vdc 4 Vdc 1 Vdc 14 mA 1200 V
SSR240 Series Output-Vac Load Specifications
Model No. Nominal
Max. Off-State Leakage
(25°C max. ambient)
120 Vac 240 Vac 440 Vac SSRL240AC10
24 to 280 Vac 10 A
1.6 V 0.1 mA 0.1 mA N/A SSRL240DC10
24 to 280 Vac 10 A
1.6 V 0.1 mA 0.1 mA N/A SSRL660AC50
48 to 660 Vac 50 A
1.6 V 0.25 mA 0.25 mA 0.25 mA SSRL660DC50
48 to 660 Vac 50 A
1.6 V 0.25 mA 0.25 mA 0.25 mA