4 Tips to Select a Right Solid State Relay?

4 Tips to Select a Right Solid State Relay

You may need a Solid State Relay. It is important to take into account the SSR performance parameters as well as the application conditions. You should also consider over-voltage conditions and SSR’s load capacity. This is essential if you want to ensure reliability and durability of your unit. These are some tips to help you choose the best SSR.

1. Take into account the load types


The units can be switched on or off under normal loads but not during heavy loads. You should choose the right unit based on your load type. This is important in order to avoid any damage to the unit. It is possible to not exceed the maximum rated current as indicated on the device.


You may also want to take into consideration surge characteristics. You should have plenty of voltage and current margin.


2. Consider the DV/DT, Transient Voltage, and Power Voltage of the Circuit


Make sure that you choose a device for direct current if you have a DC voltage system. AC Solid State Relays can control AC power and loads. Also, ensure that your load does not exceed the rated output power.


If capacitive or inductive loads are used, the power voltage will not be zero when the AC Solid State Relay is switched off. The output will have a lower DT/DV value. It is best to choose a unit with a high DV/DT.


3. Take into account the input ends of the unit


There are two types of units available: AC input control and DC input control. This unit uses a constant current source circuit. The input voltage range is between 3 to 32 volts DC. It can be connected to a microcomputer interface or TTL circuit.

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You may also want to be aware of the terminals’ negative and positive polarity. An AC Solid State Relay will have a voltage of between 70 and 285 volts.


4. Take into account the Overheating and Overvoltage as well as Overcurrent factors


The Solid State Relay can be damaged if there is a short circuit, overcurrent, or other problem. Installing an air switch or fast fuse can prevent this from happening. You can be sure to select units with MOV, RC snubber circuits and output protection. If you need the unit to withstand voltage surges, this is essential.


These units have a limited load capacity due to many factors such as temperature and ambient temperature. Ensure that the unit emits enough heat during installation and use. Install a radiator if the rated current exceeds 10 amps.


We will cut the long story short and suggest you read the following tips if you are looking to buy an SSR for your first time.