APFC Controller Panel Wiring Diagram and Connection

Hi, in this article, we are going to see the APFC Controller Panel Wiring Diagram and Connection with Capacitor Banks, Contactors, Manual Switches, Indicators, etc. APFC means Automatic Power Factor Correction. APFC controller panel is a device that is used in electrical systems to automatically correct the power factor. The power factor is a measure of how effectively electrical power is being used in a system. A low power factor can result in inefficient energy usage and increased electricity costs.

The APFC controller panel typically consists of a microprocessor-based controller, capacitors, reactors, contactors, and other necessary components. The controller monitors the power factor of the electrical system and activates or deactivates capacitors as needed to maintain a desired power factor level. 

When the power factor drops below a certain threshold, indicating reactive power is being consumed inefficiently, the APFC controller panel switches on capacitors to offset the reactive power, thereby improving the power factor. Conversely, when the power factor rises above the desired level, the controller switches off capacitors to avoid overcorrection.

Here, in this article, the APFC panel provides the function for both automatic and manual control. That means when we put it in automatic mode, it will automatically operate and in the manual mode we can manually connect and disconnect each capacitor bank separately.

Apparatus/Components

Here is the list of some apparatus and components to make a simple APFC panel,

• 4 Pole MCCB - 1 Pcs
• 3 Pole MCB - 3 Pcs
• 2 Pole MCB - 1 Pcs
• 3 Pole Contactor with 230V AC coil supply - 3 Pcs
• Capacitor / Capacitor Banks - 3 Units
• APFC Controller / APFC Relay - 1 Pcs
• NC Push Button Switches - 3 Pcs
• NO Push Button Switches - 3 Pcs
• Selector Switches - 3 Pcs
• Indicator Lamps - Red(3 Pcs), Green(3 Pcs)

Remember that here we have taken the above components with a certain as per our circuit design(e.g. here we controlling 3 capacitor banks only). You may need these components in more quantities if you want to extend this circuit.

Wiring Diagram

Here, in the below wiring diagram of an APFC Panel, you can see the connection between Circuit Breakers, Contactors, Capacitor Banks, APFC Controller, Switches, Indicator lamps, etc.

Connection Description

Power Circuit Connection

The input of all three 3-pole MCBs is connected to the output of the MCCB. The output of the MCBs is connected to the input of their respective 3-pole contactors. Then the output of the contactors is connected to their respective capacitor banks.

Control Circuit Connection

APFC Controller/Relay Connection

The L1 and L2 Terminals of the APFC controller are connected to the R and Y phase output of the MCCB through a double pole control MCB. The relay common terminal of the APFC controller is also connected to the R phase. The output terminals e.g. C1, C2, and C3 are connected to their respective selector switches(to the 'Auto Terminal'). The S1 and S2 terminal of the APFC controller is connected to the CT or Current Transformer that is installed with the 'B' Phase.

Selector Switch Connection

The common terminal of the selector switches is connected to the A1 terminal(contactor coil) of their respective contactors. The 'Auto' terminal of the selector switches is connected to the relay outputs of the APFC controller. The 'Manual' terminal of the selector switches is connected to their respective push-button switches for manually turning on and off.

Push Button Switches Connection

Here, a combination of an NC push button switch(for Off) and a NO push button switch(for ON) is used for each contactor. First of all, a phase supply (here we take from R phase output from the control MCB) is connected to the input of the NC switch, and the output of the NC switch is connected to the NO switch then the output of the NO switch is connected to the manual terminal of their respective selector switch. Here, both input and output terminals of the NO switch are connected to the NO contacts of their respective contactors to make the contactor hold once the NO push button switch is pressed.

Indication Lamp Connection

Here, two indicator lamps(Red for Indicating On and Green for indicating Off) are used for each capacitor bank. You can see the Red indication lamp is connected to the power supply through the NO contact of the contactor, so when the contactor is turned On which means the capacitor bank is connected or turned On the Red indication lamp will glow. Similarly, the Green indication lamp is connected to the power supply through the NC contact of the contactor, so when the contactor remains in the off condition which means the capacitor bank is disconnected or off the Green indication lamp will glow.

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• Automatic Phase Reverse Protection Circuit using Sequence Relay

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