Nothing close enough? Start from a blank circuit diagram → Describe it in one paragraph.
How to use a circuit diagram template.
- 01Add the hydraulic valve solenoid
Place the solenoid coil (or valve symbol with coil) at the output side of the relay to represent the hydraulic valve actuator.
- 02Place the relay and control contacts
Add a relay with a coil and one or more normally-open or normally-closed contacts, and wire the control signal to the coil.
- 03Wire power and protection
Connect the power supply through the relay contacts to the solenoid, and include a flyback diode or surge suppressor across the coil to protect the switching device.
- 04Add emergency stop or PLC interface
Insert any safety relay contacts, emergency stop buttons, or PLC output modules in series with the coil circuit as required.
- 05Label and export
Label components and wire numbers, then export the schematic for panel build or documentation.
Questions about circuit diagram templates
Why use a relay to control a hydraulic solenoid valve instead of driving it directly from a PLC output?
A relay isolates the PLC output from the inductive solenoid load and allows you to switch a higher current or different voltage than the PLC can handle directly. It also provides a convenient place to add hard-wired safety contacts.
Do I need a flyback diode across the relay coil or the hydraulic valve solenoid?
Yes, if the coil is switched by a transistor or PLC output, a flyback diode across the coil suppresses the voltage spike when the magnetic field collapses. If the relay coil is driven by a mechanical switch, a diode is still good practice to reduce arcing and protect nearby electronics.
Can I use the same relay for 12V and 24V hydraulic valve solenoids?
The relay contact rating must match the voltage and current of the solenoid. A relay rated for 24V DC at the required current may not be suitable for 12V at higher current; always check the contact rating for the load you are switching.
How do I add an emergency stop to a hydraulic valve relay control circuit?
Wire an emergency stop button or safety relay contact in series with the relay coil circuit so that opening the E-stop de-energizes the relay and removes power from the valve solenoid.
Can I use a 24V DC PLC output to switch a 120VAC hydraulic valve?
Yes, use an interposing relay: the PLC output drives the relay coil (24V DC), and the relay contacts switch the 120VAC supply to the valve solenoid.