Solid state relay selection method thermal, necessary, material, because

传奇客服

Solid state relay
selection method
1 in the selection of small current specification of printed circuit board using solid state relay, because the lead terminal for high thermal conductivity material, the welding should be less than 250 ℃, time is less than 10S conditions, such as ambient temperature causes, may be necessary to consider derating use, generally with the load current control in rated value of less than 1/2 use.
2 kinds of load surge characteristics of solid state relay SSR selection
Controlled load on moment will have a great surge current, due to heat not sporadic, is likely to make the SSR internal SCR damaged, so the user in the selection of relay when the response to the charged load surge characteristics are analyzed, and then select relay. The relay to ensure steady work condition to withstand the surge current, selection may refer to table 2 load derating factor ( room temperature).
If the selected relay need more frequent in work, life and reliability higher occasions when working, should be in again on the foundation of 2 multiplied by 0.6 in order to ensure reliable work. In the selection the general principles, in the lower voltage requirements for signal distortion can be selected using field effect tube as the output device of DC solid state relay; such as the AC resistance load and the majority of the inductive load, can choose zero type relay, which can prolong service life of the load and relay, also can reduce its radio frequency interference. Such as phase output control, should choose a random type solid state relay.
The 3 use of the influence of environment temperature
Solid state relay load capacity affected by environment temperature and the temperature influence, in the process of installation, must be ensured to have good heat dissipation condition, rated working current in 10A above products should match the radiator, above 100A products should match the radiator fan strong cold. In the installation should pay attention to the bottom and the good contact of the relay radiator, and considering the amount of heat conductive silicone grease coating in order to achieve the best cooling effect.
Such as a relay of long-term work in the condition of high temperature ( 40 ℃ ~80 ℃), the user can according to the manufacturers to provide the maximum output current and environmental temperature curve data, consider derating use to ensure normal work.

A 4 over-current, over-voltage protection measures
In the relay is used, because of over-current and short circuit load will cause SSR solid state relay internal output controllable silicon permanent damage, may be considered in the control loop to increase fast fuse and switch the air to protect type ( select relay should choose products output protection, built-in pressure-sensitive resistance absorption circuit and RC buffer, absorbing surge voltage and improve dv/dt tolerance ); also in the output terminal of the relay is connected with the RC absorption circuit and pressure sensitive resistor ( MOV ) to achieve output protection. Selection principle of 220V using 500V-600V varistor, 380V can use 800V-900V varistor.

The 5 relay input signal
When in use for high input voltage and input current is too large beyond its specified rated parameters, may be considered in the input end is connected in series with a divider resistance or at the input port and a shunt resistor, to the input signal does not exceed the rated parameter value.

6 in specific use, the control signal and the load power requirements for the stability, fluctuation should not be greater than 10%, otherwise it should take precautions.

7 when in installation should be kept away from electromagnetic interference, radio frequency interference source, in order to prevent the malfunction of out of control.

8 solid state relay circuit and the load terminal voltage, output will have certain leakage current, in use or design should pay attention.

9 solid state relay failure replacement, should try to use the original, or technical parameters in exactly the same product, so that with the original application line matching, to ensure a reliable system working.
Reference link legend Mall (http://www.315mro.com )