RO Plant Control Panel Wiring Diagram

Admin@AKR Technical

The control supply can be supplied to the RO Plant control panel from the dual pole MCB or single pole MCB used for power wiring for the control supply. The control system is fully designed by 230V AC supply.

RO Plant Control Panel Wiring Diagram

RO Control Panel Wiring

To start the control wiring, connect a wire feed water pump contactor OLR - NC 95  terminal from the output (Phase supply) on the right side of the MCB. The next wire connects to terminal block 1 from OLR - NC (96). This wire is the first point of the terminal block. Connect this connection to the common point of the float switch on the raw water tank. The normal open (NO) second point of the float switch is connected to the bottom of the second point of the terminal block.

Feed Water Tank Float Switch Function in RO Plant 

The function of the float switch helps for dry run protection of RO pumps. This float switch is commonly used to prevent the RO plant system from operating if there is not enough water in the feed water tank (Raw water tank). This is the first very important protection of this water pumping system. This method provides dry-run protection for both manual and automatic operations. The wire connection from the second wire (NO) of the float switch on the below terminal connect to the second terminal bottom. In the terminal block a wire is connected from the top of this second terminal to the common point below the hand auto switch. This connection provides dry run protection in both hand and auto positions. The next step is the hand-position control wiring.

RO Plant Hand Position Control Wiring

Connect a connection stop to the push button from the hand position position for hand mode control wiring. Connect a wire feed from its output to the starting PB and from its output to the A1 of the water pump contactor. A loop from contactor A1 should connect to point NO 13 of the same contactor. Give a loop to point 14 of the same NO from the stop push button. This is done in order to catch the contactor. The neutral point A2 can then be connected. The auto control connection must also be connected for operation of the high pressure pump in the hand mode.

Automatic control wiring in RO Control Panel

To connect the RO automatic control, connect a wire from the hand auto switch to the SPST (Single Pole Single Throw) switch on the right side output. The wire feed from the output of this switch connects to the water pump contactor point A1. Connect a wire from the input point or auto point of this SPST switch to the OLR - NC 95 of the second contactor, which is the high pressure pump contactor overload relay. The next step is to connect a wire from 96 of this OLR - NC to the top point of the third terminal of the terminal block. Connect a bit of wire from the bottom of the third terminal of the terminal block to any point on the normal open (NO) point of the pressure switch. A bit of wire should be connected to the second point of the pressure switch and to the bottom of the fourth terminal of the terminal block. This is to protect the high pressure pump and RO system from working at low pressure.

RO Plant Control Panel Wiring Diagram

The connection from the top of the fourth terminal is connected to the stop push button of the second contactor and from there to the start push button. The high pressure pump from the start push button outlet should be connected to point A1 of the contactor to the outlet and from there to point NO -13 of the same contact. Then loop a wire from the output of the stop push button to point 14 of the same NO auxiliary contact. This (NO) connection allows to hold the magnetic contactor continuously while releasing the push button by pressing the start push button on the hand position. This is an example of how it works with a simple direct online (DOL) connection.

Second Float Switch Function in RO Plant 

A float switch must be plugged into the RO storage (Mineral water) tank for automatic operation, which must be connected to terminal 5 and 6. A loop wire 4 to 5 is already attached to the terminal block connector. The supply into terminal 5 is only available when the pressure switch is closed. That means, when the pressure reach into the pressure switch maximum set point. Distribution to the sixth terminal is via the NC (Normal Close) of the float switch.

ON-Delay Timer Wiring and Function

The ON-Delay timer coil from terminal block point 6 connects directly to terminal A1, from where a loop connects to common point 15 of the same timer. A wire is connected from NO point 18 of the ON-Delay timer to point A1 of the second contactor (HPP Contactor). Look at the given picture and see the connection.

Now the next step is to connect the neutral at all A2 points. You can understand it by looking at the Control wiring picture.

RO System Backwash Switch Connection

You can see that a switch is connected into the auto system. Let me tell you why. The switch provided for RO system auto position should be turned off during back washing of the sand filter and carbon filter.This is an extra protection to prevent the high pressure pump from working during back-washing. If connected without this switch, the supply return to the auto point from the first electromagnetic contactor A1 in hand operation.

You can turn it off and backwash the sand filter and carbon filter in hand mode safely. The system will only operate in automatic mode if this switch is turned on after the backwash. Now our RO system control wiring is complete.


This RO plant panel applies a very simple wiring methods control the plant devices. So you can make this RO plant control panel is very easily. It is one of the simplest and most reliable control panel for the best RO system with low cost maintenance. We hope you find this article useful. Thanks to choose our website ( for your better knowledge in RO control panel wiring. Follow our website to know more about control panel wiring and electrical engineering work.

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