Solid state relay question

[Gary Campbell]

Here is a schematic showing how to wire a relay to control a spindle brake. Power from a power supply provides common to the device and the power goes thru the relay

https://www.centroidcnc.com/dealersuppo ... 007.r3.pdf

[Richards]

Here's a simple schematic based on the schematic that Gary posted that shows one way to wire a SSR to control a motor or other AC load. The Double Pole Single Throw switch can be any of the relays on the Acorn relay board or one of the relays on the 16x16 I/O expansion board. When the DPST relay is closed, 24 volts flows through the SSR's DC control circuit turning on the SSR AC circuit which allows AC power to flow through the motor or other AC device. It's good practice to protect circuits with fuses or circuit breakers. The schematic shows one example of using fuses to protect the AC circuit and the DC control circuit.

(Note: There are two types of SSRs. The type I use has a zero-crossing detection circuit built in. That means that the SSR turns on/off when the AC signal crosses the zero voltage point on the AC sine wave. That type of SSR has very moderate EMI. The other type of SSR instantly turns on/off the AC circuit. That type of SSR is normally used to control the brightness of lights. It can produce a lot of electrical interference and it usually operates at a much higher temperature. To turn a motor on/off or to turn a machine on/off, an SSR with zero-crossing detection works best.)