What is the control side of a relay?
The Control Circuit is the part of the relay that determines when the output component is energized or de-energized. The control circuit functions as the coupling between the input and output circuits. In electromechanical relays, the coil accomplishes this function.
Where might a control relay be used?
Control relays are electronic parts that are used in motors, power plants, power supply systems, transistors, and more. Control relays permit a low current circuit to control a high current circuit. Control relays are coils that have electricity sent through them.
Which device is used to control a relay?
A solid-state relay uses a thyristor, TRIAC or other solid-state switching device, activated by the control signal, to switch the controlled load, instead of a solenoid. An optocoupler (a light-emitting diode (LED) coupled with a photo transistor) can be used to isolate control and controlled circuits.
Why would you implement a relay to in a PLC system?
Relays are used to isolate one voltage level from another. A relay is used to energize the starter, which, in turn, switches the motor voltage while the PLC controls the relay. Wired to provide a control sequence, relays may also be used for simple control schemes where a PLC would prove uneconomical.
What are the three types of relay?
The three main types of relays are electromechanical, solid-state, and reed.
What are the contacts on a control relay?
Contacts are usually of the normally open/normally closed (NO/NC) or Form C style, in quantities of one, two, three, or four poles per relay. The relays are built with fixed quantities of contacts. Plug-in relays plug into sockets; sockets may be mounted directly to a panel or they may be mounted on DIN rails.
Where does the current go in a 5 pin relay?
Current splits inside the relay, supplying power to both the control and load circuits. A 5-PIN relay has a single control circuit, but two separate current paths for the switch: One when the relay is de-energized (OFF – no current through the control coil) and the other the energized (ON – current is flowing through the control coil).
What are the test buttons on a NEMA relay?
Test buttons, a useful feature on some plug-in relays, allow manual actuation of the relay contacts. Manual actuation can be helpful when you’re troubleshooting circuits while voltage is not applied to the coil. Conventionally, the term “machine tool relay” is applied to NEMA-style relays.
How to determine the resistance of a relay?
**The relay (SRD-05VDC-SL-C) is a single pole double throw (SPDT) type relay. 1. Same as previous parts, let’s start with determining the relay coil pins using a multimeter. Set the multimeter to resistance measuring mode with a scale of 1000 ohm since the coil resistance normally ranges between 50 ohm and 1000 ohm.
Where is the ignition relay located in a car?
The ignition relay is often located in the fuse box under the hood. It can also be located in a fuse box under the dashboard inside of the car. The ignition relay’s exact location may differ from vehicle to vehicle depending on the design of the vehicle and the company that manufactured it.
How to identify terminal pins of a relay?
Set your multimeter to continuity test mode. Try to touch the probes of multimeter on remaining pins to determine which are the pins actually connected with each other.These pins actually consist of normally closed (NC) pin/pins and common pin/pins. Based on this finding, the remaining pins must be normally open (NO) pins.
How is a relay connected to a control circuit?
When you trigger the relay (by applying the appropriate voltage across the control circuit), the common connection switches to the other side. When you connect your circuit to the NO (normally open) and Common connectors, the circuit remains open until an appropriate voltage is applied to the IN1 connector on the Control circuit.
Where does the power come from on a Ford EEC relay?
This voltage comes from the ignition switch. Power (in the form of 10 to 12 Volts) is always present in circuit 4 . This voltage comes directly from the battery positive terminal across a fusible link on the starter motor solenoid (on the fender). Ground is always present on circuit 1.