How to Connect a Solenoid Coil?
Solenoid coils are used to operate valves, they use an electrical current to energise an electro-magnetic coil. This exerts a force on the ferrous core of the valve, and in turn open or close the valve mechanism.
Solenoid coils are used when the flow of a gas requires controlling. They are not used for regulating the flow of gas, this is generally done with an in-line regulator such as this 0.5-10 Bar one.
How are Solenoid Coils Rated?
Power input
This is the type and amount of power the coil needs to operate, alternating or direct current, and the voltage required. Common Voltages are 5V and 12V DC, and 110V and 220V AC. The coil also has a power rating, this is how much energy it requires to work, this information is useful for specifying your control circuitry and wiring. The power rating is in watts, eg. 3W.
Core Diameter
This is the diameter of the core of the valve the coil is operating, eg. 12mm
Dimensions
The overall size of the unit is required for planning and designing layouts
Electrical Connection
- DIN, this is a standardised plug that removes the need to connect individual wires. A lot of solenoid coils use this.
Insulation Rating
- Class F 155°. This is the maximum temperature the device can withstand in operation. Higher than this and the insulation on the coil will degrade causing damage.
IP Rating
This is the level to which the coil can resist water and dust ingress. eg. IP65
How to Connect a Solenoid Coil:
Solenoid coils are simple to connect, they will generally only use 3 wires, one of these is the earth, which will be labelled, often the other two connect to the switching power are unlabelled. In both AC and DC coil solenoid coils, the polarity of the power connections is not vital.
Step by Step Instructions
- For DIN type connectors, unscrew the phillips head screw holding the plastic connector housing to the solenoid
- Slide off the plastic housing
- Pull the DIN connector off of the pins on the coil
- Unscrew the valve stem screw securing the coil to the valve
- Remove the coil
- Repeat in reverse to re-install
Earth or Ground Connection
Particularly vital in high voltage applications for safety, the earth is generally connected to any metal on the device. Be mindful, however that some complex machinery will have dedicated earthing points. This is because earth faults routed through other electronics such as PCBs can cause serious damage. Earthing points are almost always denoted by the symbol below, or with yellow/green wiring.
Positive and Negative Terminals
The electromagnets that activate AC solenoid coils will usually activate regardless of polarity, but in the case of DC solenoid coils, the positive and negative leads need to be in the correct orientation.
The safest way is to replicate the original wiring, and ensuring the pinout of the old and new coils are the same.
Considerations
When installing or replacing solenoid coils , there are some elements to be aware of. The first is the electrical connections, these should be isolated and checked before work is commenced. Whilst 5v and 12v supplies are not as dangerous, 220v power can cause serious injury and a professional should be consulted if there is any uncertainty.
High pressure pipework can cause serious injury if mistreated, always ensure systems are not pressurised or are safe to work on before removing solenoids or valve components.