How to connect the wires to the single-head solenoid reversing valve

The wire connection of the single-head solenoid directional valve needs to be operated according to its voltage type (DC or AC) and specific wiring terminals. The following are detailed steps and precautions:

1. Preparation before wiring

Confirm voltage type

Direct current (DC) solenoid valve: It is necessary to distinguish the positive and negative poles (usually marked '+' and '-'). Reverse connection may cause non-operation or damage.

AC solenoid valve: No need to distinguish polarity, live and neutral wires can be connected arbitrarily.

Check the voltage value: Make sure the power supply voltage is consistent with the rated voltage of the solenoid valve (such as 24V DC, 220V AC, etc.).

Identify terminal blocks

Two-wire solenoid valve: usually power wire (positive/live wire, negative/neutral wire), some with grounding terminal (yellow and green two-color wire).

Three-wire solenoid valve: may include common terminal (COM), normally open terminal (NO), normally closed terminal (NC), which need to be connected according to the control logic.

Solenoid valve with indicator light: The indicator light wire must be connected according to polarity, otherwise it will not light up but will not affect the function.

Power off operation

The power supply must be cut off before wiring, and use a test pen to confirm that there is no power before proceeding to avoid electric shock or short circuit.

2. Specific wiring steps

1. Direct current (DC) solenoid valve wiring

step:

Connect the positive (+) terminal of the power supply to the positive terminal of the solenoid valve (usually the red wire or marked '+').

Connect the negative (-) terminal of the power supply to the negative terminal of the solenoid valve (usually the black wire or marked '-').

If the solenoid valve has a ground terminal, use a yellow and green two-color wire to connect it to the equipment ground bar.

Example:

24V DC solenoid valve: The red wire is connected to 24V+, and the black wire is connected to 24V-.

With indicator light: The positive pole of the indicator light is connected to 24V+, and the negative pole is connected to the negative pole of the solenoid valve (or the current is limited through a resistor).

2. AC solenoid valve wiring

step:

Connect the live wire (L) to any of the solenoid valve terminals (usually the brown or blue wire).

Connect the neutral wire (N) to the other terminal block.

Connect the ground terminal (if any) as described above.

Example:

220V AC solenoid valve: brown wire is connected to the live wire, blue wire is connected to the neutral wire.

3. Control through intermediate relay (recommended scenario)

Applicable situations:

The solenoid valve has a large power (such as exceeding the relay contact capacity).

The control circuit needs to be isolated (for example, the PLC output does not match the solenoid valve voltage).

step:

Connect the coil of the intermediate relay to the control circuit (such as PLC output signal).

Connect the power wire of the solenoid valve to the contact of the intermediate relay (normally open contact NO).

When the control signal is triggered, the relay is closed and the solenoid valve is powered on.

Advantages:

Protect control equipment (such as PLC) from large current surges.

Implement low voltage control of high voltage solenoid valves.

3. Post-wiring inspection and testing

Check the connection:

Make sure all connections are secure and there are no loose or exposed wires.

Check whether the ground wire is reliably connected.

Power-on test:

Turn on the power slowly and observe whether there is any abnormal sound or heat in the solenoid valve.

Manually trigger the control signal (such as button, PLC output) to verify whether the solenoid valve operates normally.

Function verification:

Combined with the cylinder or hydraulic system, check whether the reversing function is as expected (such as cylinder extension/retraction).

Monitor whether the solenoid valve indicator light (if present) is on.

4. Common problems and solutions

The solenoid valve does not operate:

Check whether the power supply voltage matches and whether the wiring is loose or reversed (DC valve).

Measure the coil resistance (normal value is tens to hundreds of ohms). If it is infinite, the coil is burned out.

The indicator light is off but the solenoid valve works:

The indicator light circuit is faulty or the polarity is reversed, which does not affect the function but needs to be repaired.

The solenoid valve is overheating seriously:

If the voltage is too high or the coil is short-circuited, immediately cut off the power, check and replace the solenoid valve.

Intermittent work:

If there is poor contact or voltage fluctuation, check the tightness of the terminals and install a voltage stabilizer if necessary.

5. Safety precautions

Explosion-proof environment:

An explosion-proof solenoid valve must be selected (such as Ex d IIC T6 level), the cable entry device must use an explosion-proof gland, and the grounding resistance is ≤4Ω.

Protection level:

Select the IP level (such as IP65 dustproof and waterproof) according to the installation environment, and avoid using the ordinary type in the open air or humid places.

Maintenance cycle:

Regularly check the sealing of the solenoid valve and clean the air source filter to prevent impurities from entering and causing failure.