Cheonsei Metering Pump Wiring: Motor, 4-20mA and Level Switch

Cheonsei metering pump wiring comes down to three circuits: motor power, the external control signal and the tank level interlock. A standard Cheonsei KD pump is a motor-driven mechanical diaphragm pump, so it only needs a three-phase motor supply. The 4-20mA input and feedback appear only on pumps ordered with the BLDC control unit, option code A, such as the KDV-A. A low level switch normally sits in the control panel rather than on the pump.

This guide to cheonsei metering pump wiring is for electricians and panel builders. It sticks to what the KD manuals and catalog actually show. Where a terminal number is not legible or not published, follow the manual for your exact model rather than guessing.

Cheonsei metering pump wiring for the motor supply

The Chinese KD manual lists the standard supply as 50 Hz, 220/380 V. The English manual describes the standard motor as a 220/380 V and 440 V three-phase combination. Before connecting anything, confirm that site voltage and frequency match the motor nameplate, then follow the diagram inside the terminal box cover.

In cheonsei metering pump wiring, the difference between 220 V and 380 V is how the links sit in the terminal box:

• For 220 V, the links make a delta connection.
• For 380 V, the links make a star (Y) connection.

Put the links in the wrong position and the motor draws too much current or burns out. Single-phase and special motors are wired differently, and the manual asks you to consult the supplier in those cases.

Protection devices

The manual calls for grounding both the motor and the equipment, with fuses and thermal protection sized to the nameplate. The English version also asks for a specified magnetic switch and thermal relay for control and maintenance. In practice, Cheonsei metering pump wiring always runs through a panel with a breaker, contactor and overload relay, since the pump has no start button of its own.

Checking rotation before anything else

Rotation is not shown on a typical Cheonsei metering pump wiring diagram, yet getting it wrong causes the most trouble. The English manual states the motor should turn clockwise viewed from the fan cover, and the Chinese manual says it must match the arrow on the pump body. If it runs backwards, swap any two of the three phase wires.

Jog the motor with the stroke set to 0% first. The manual then runs the pump at 0% and at 100% stroke for 30 to 60 minutes each before raising pressure. In cold weather the motor current is usually high for a while after start-up because the gearbox oil is thick; it settles after running unloaded.

Cheonsei metering pump wiring on KDV-A BLDC units

For proportional dosing, Cheonsei offers the BLDC control unit, option A. For cheonsei metering pump wiring on this unit, the catalog lists four connection groups:

1. Power: single-phase 220 VAC or three-phase 220/380 VAC. The KM-A series uses single-phase 110 to 220 V only.
2. Remote control signal input: a 4-20mA signal from a PLC or controller, mapped to 0 to 100% of full flow.
3. Analog output: an isolated 4-20mA feedback signal, 250 Ω maximum load, ready for a PLC input.
4. FG: frame ground.

The catalog gives an effective flow range of 5 to 100% of full scale with ±2% accuracy. The front keys switch between manual and automatic mode. Exact terminal numbers and shield termination are not clear in the scanned catalog, so check the manual for your model.

Use shielded cable for the 4-20mA signal and keep this part of the cheonsei metering pump wiring away from motor power. Erratic flow on site is usually traced to signal and power cables sharing one tray.

A standard KD pump can also be made proportional with a VFD on the motor, with the 4-20mA wired to the drive. That is panel design, and the drive manual governs the terminals.

Where the level switch goes

Low tank level shutdown is standard on any dosing skid, but the KD documents show no level input on the pump itself. Typical Cheonsei metering pump wiring for the level switch looks like this:

• Wire the switch contact in series with the contactor coil, so a low level drops out the contactor and stops the motor.
• Take a second signal to an alarm or the PLC so operators know to refill.
• On BLDC units, whether the remote input can accept a stop signal depends on the model manual. Do not assume.

We generally suggest two level points: a low alarm and a low-low trip. With a single point, the pump stops the moment the alarm sounds and nobody has time to refill.

Safety before and after wiring

The manual is clear on the basics of safe cheonsei metering pump wiring. Do not work with wet hands, leave the wiring to a qualified electrician and use standard components. Isolate the power and lock it out before any inspection. If the pump handles acid, caustic or hypochlorite, relieve line pressure and wear gloves and eye protection before opening the head.

After wiring, do not jump straight to full pressure. Confirm rotation, run the stroke sequence, then raise pressure slowly while checking that motor current stays within its rating.

Conclusion

Start any Cheonsei metering pump wiring job by confirming whether the pump is a standard KD or a BLDC unit with option A. The standard pump needs delta or star connection to match the nameplate, a contactor and overload relay, and a rotation check. The BLDC unit adds 4-20mA input, isolated feedback and frame ground. The level switch belongs in the panel interlock. For more, compare Cheonsei KDV and KDH pumps, read the general diaphragm metering pump wiring guide and the low level alarm setup. Browse mechanical diaphragm metering pumps and level switches, or send your model and nameplate photo and contact our engineers to check the wiring.

FAQ

Can a Cheonsei KD pump run on single-phase 220 V?

Not the standard three-phase motor. Order a single-phase motor or a BLDC unit and state it on the order.

What happens if the motor runs backwards?

The pump may deliver little or nothing, and long reverse running is hard on the gearbox. Swap two phase wires to fix it.

Does the pump stop if the 4-20mA signal is lost?

The catalog does not say. Check the model manual and test it during commissioning so you know the behavior.

Where does the feedback signal go in cheonsei metering pump wiring?

The isolated 4-20mA feedback goes to a PLC analog input to show the actual set flow. Keep the loop load at or below 250 Ω.

Can the level switch break the motor power directly?

It is not recommended. Level switch contacts are small, so wire them into the contactor coil and let the contactor switch the motor.