What should the PF be for a random turn on relay?
Inductive Loads (motors, contactor coils, transformers) – pf <0.75; Random turn-on relays are usually recommended for these types of loads as the phase shift between voltage and current may cause problems with some zero-crossing relays.
Why does a solid state relay not turn off?
It is due to the fact that the SCRs in the output circuit cannot turn off until the load current falls below their specified holding current (typically less than 100mA). This is a characteristic of all AC output solid-state relays, regardless of the switching type.
When does a synchronous solid state relay switch?
Also known as a “synchronous” solid- state relay, this is the most common type of SSR found in the market today. As the name implies, the switching of the relay from a non-conducting to a conducting state occurs when the AC mains voltage reaches the zero-crossing point of the sine-wave.
How does zero crossing work in a relay?
The zero crossing only refers to when the switch closes (or opens). So when you apply a control voltage, the relay waits until a zero crossing and closes and remains closed. When you remove the control voltage the relay waits until a zero crossing and opens. The delay is only a part of one 60Hz cycle on each end.
It is due to the fact that the SCRs in the output circuit cannot turn off until the load current falls below their specified holding current (typically less than 100mA). This is a characteristic of all AC output solid-state relays, regardless of the switching type.
Inductive Loads (motors, contactor coils, transformers) – pf <0.75; Random turn-on relays are usually recommended for these types of loads as the phase shift between voltage and current may cause problems with some zero-crossing relays.
Also known as a “synchronous” solid- state relay, this is the most common type of SSR found in the market today. As the name implies, the switching of the relay from a non-conducting to a conducting state occurs when the AC mains voltage reaches the zero-crossing point of the sine-wave.
The zero crossing only refers to when the switch closes (or opens). So when you apply a control voltage, the relay waits until a zero crossing and closes and remains closed. When you remove the control voltage the relay waits until a zero crossing and opens. The delay is only a part of one 60Hz cycle on each end.