About choosing correct Delcon relay type

For choosing correct relay type to your application you need to know do you need input relay or output relay.

• Input relays are used to read on/off information from sensors and limit swithces.
• Output relays are used to control loads such as contactors, magnetic valves, lightnings and motors.

All Delcon type of solid state relays are isolated by means of pulse transformer. It guarantees over 4 kV galvanic isolation between circuits.

All Delcon solid state relays tolerate high interferences in signal lines which are very common in automation industry.

Also all Delcon solid state relays have 100 % safe status indication.

How to choose input relay

When choosing input relay type you need to know:

• Control voltage of the relay (input voltage); Voltage and is it AC or DC.
• Type of the sensor and length of the signal wire

With input relays you normally don't have to think about switching voltage (load) because operation range for Delcon relays is 
0 VDC...60 VDC.

Input relays are normally connected to logics or other interfaces where normal voltage level is 24 VDC.

Choose relay type where control voltage is same with voltage level (V) and type (AC or DC).

If control voltage is DC then choose appropriate SLI ...CR relay type.

If control voltage is AC then check the sensor type:

• If sensor is two wire sensor (proximity sensor) then choose SLI ...CRP type of relay
• In other cases choose SLI ...CR type of relay.

If high energy spikes are expected in singnal lines then choose SLI ...CH type of relay.

How to choose output relay

When choosing output relay type you need to know:

• Control voltage of the relay (input voltage, V)
• Load voltage (V) level and type (AC or DC)
• Maximum current of the load

Most common control voltage (input voltage of the relay) for output relays is 24 VDC.

Delcon output relays are available for several DC control voltages and for few AC control voltages.

Choose the relay type which have correct control voltage (V) and voltage type (AC or DC), correct load voltage range (V) and voltage type (AC or DC), and high enough maximum current (A).

Please check the load type:

DC-Load:

• If load is resistive DC-load choose SLO ...CR
• If load is inductive DC-load (e.g. magnetic valve) choose SLO ...CRA or SLO ...CRA4 (no need for extra diodes in the poles of the load) or SLO ...CR or SLO ...CRX (in these cases clamp diode need to be used on the poles of the load, however this lengthens the off delay dramatically.
• If DC-load is over 60 VDC, choose SLO ...CRA, SLO ...CRA4 or SLO 24CRAA4.

AC-Load:

• If load is contactor, lighting or resistor load, then choose SLO ...TR
• If you need as short off delay as possible then choose SLO ...IRA
• If load is motor load (1 phase motors on/off and reverse) then choose SLO 24TRA.

All Delcon solid state relays have clear on and off point voltage level. No minimum requirements for load and leakage currents are extremely low.