3 Phase Line PFI Panel Star Delta Connection and PF Calculation

3 phase 15 KVA PFI

3-phase 15 kVA PFI unit is used to improve power factor in electrical systems by providing reactive power compensation through capacitor banks. It reduces power losses, enhances voltage stability, and ensures efficient operation of 3-phase loads, often applied in factories, commercial buildings, and industrial plants.

power-factor-capacitor-bank-connection

Learn 3-phase line PFI panel wiring, star-delta starter connection, and PF improvement with step-by-step installation, work process, and testing guide.

star delta starter connection:

In the industries, a 3-phase line PFI panel that is connected in star-delta is used to control the loads of the motor and enhance the power factor. Reactive power is regulated by the PFI panel using capacitor banks, and the star-delta starter provides a safe start of the motor. All these work together to make things more efficient, safer in terms of power bills, and equipment protection.

3 phase line protection relay:

A 3-phase line PFI panel connected in star-delta will guarantee that the motor will work efficiently and the power factor will be better in industrial systems. PF is improved using capacitor banks and APFC relays on the PFI panel, and the star-delta starter decreases starting current in 3-phase induction motors. Such a combination reduces the losses of energy, eliminates the penalties of utilities, and ensures stable operation. Protection relays are used to protect the system against overcurrent, earth faults, and voltage changes. To facilitate the load management, it is necessary to ensure that the HT supply is properly wired to the LT panel and the star-delta starter and PFI panel are connected. With the PF being corrected to a value near unity, the efficiency and reliability of the entire system are enhanced.

⚡ Work & Installation (Input → Output):

HT Line enters the transformer (11kV/33kV → 400V LT).
LT Panel distributes 3 phase supply to busbars.
Star-Delta Starter connects to induction motors for safe starting.
PFI Panel (Capacitor banks + APFC relay) connects parallel to busbar.
System maintains PF close to unity and protects motors via relays.

Testing & Final Adjustments:

The system should be subjected to intensive testing after wiring. Check insulation resistance, permanency, and relay operation. Output of the check transformer LT to a balanced 3-phase voltage. Test the star-delta starter. Run motors, test to ensure a smooth transition between star and delta with no trips. Check the switching of the APFC relay and the capacitor bank to check the PFI panel operation. Regulate capacitor stages to sustain PF at 0.95 -1.0 at different loads. Test that the fault simulation with overload and earth fault relays operates correctly. Measure starting current, running current,t, and PF of the recmotor before switching to the capacitors. Load test in various conditions to ensure a stable operation. Lastly, seal all terminations, verify correct earthing, and issue a log sheet of test results.

Frequently Asked Questions - power-factor-capacitor-bank-connection:

What is a PFI panel?

A PFI panel improves power factor using capacitor banks and APFC relay.

What is star delta connection?

A motor starter method that reduces starting current by connecting windings in star, then delta.

Why use PFI panel in industries?

To reduce electricity bills, improve efficiency, and avoid penalties for low power factor.

How is PFI panel connected?

It is connected parallel to the LT busbar for automatic capacitor switching.

What is APFC relay?

An Automatic Power Factor Controller relay that controls capacitor switching based on load.

What is the formula for 3 phase current from kVA?

I = (kVA × 1000) / (√3 × V).

What protections are used in 3 phase system?

Overcurrent relay, earth fault relay, under-voltage, overload, and differential protection.

What voltage is used for LT panel?

Typically 400V 3 phase line-to-line, 230V line-to-neutral.

Why star delta starter is used?

It reduces high inrush current during motor starting, protecting equipment.

What is unity power factor?

When real power equals apparent power (PF = 1), indicating maximum efficiency.

Tags: 3 phase PFI panel wiring star delta starter connection power factor improvement panel 3 phase line protection relay capacitor bank wiring APFC relay connection star delta motor starter wiring LT panel connection 3 phase load calculation transformer to LT line