MV Capacitor Sizing

MV CAPACITOR SIZING CALCULATION

Prepared for: Project :

Karaikal Port Project Phase -II (Stage-I)

Customer :

MARG Limited

End User :

MARG Karaikal Port Limited

Consultant :

HOWE India Private Limted

Prepared by: FLSMIDTH PRIVATE LIMITED

34,EGATOOR, KELAMABAKKAM CHENNAI - 603 103, (TAMILNADU) (TAMILNADU) INDIA TEL. 0091-44-4748 3000 / 2741 3000 FAX. 091-44- 2747 0301 /302

Ver.

Date

Designed

Checked

Approved

1.0

27.04.2011

SARRN

SARKN

SRRN

Description

Initial Issue

The information transmitted by this document is proprietary and confidential property of FLS and may not be duplicated disclosed or utilized without written consent from FLSMIDTH.

MV CAPACITOR SIZING CALCULATION FLSmidth Private Limited Project : Karaikal Port Project Phase -II (Stage-I) Customer : MARG Limited End User : MARG Karaikal Port Limited Consultant : HOWE India Private Limted 6.6 kV Switchboard at SS-1 Bus-1

Switchboard Load

= 3055.49

kW

System Voltage

= 6.6

kV

PF Improvement

= 0.8 to 0.9

Lag

kVAR required for PF Improvement @ 6.6kV

= (kW Rating) x (PF Correction Factor) = (kW Rating) x { [tan (arccos 0.8)] - [tan (arccos 0.9)] } = 811.78

Voltage at 6.6 kV Bus

= V

Voltage drop at Reactor

= VL

Voltage drop at Capacitor

= Vc

Inductive Reactance (Ohms/ph)

= XL

Capacitive Reactance (Ohms/ph)

= Xc

Reactance of Eq circuit(Ohms/ph)

= Xeq

Current through the Equivalent circuit

= ICL

Voltage equation of circuit

= V = Vc - VL

kVAR

Xeq = Xc -XL Xeq = Xc - 0.06 Xc Xeq = 0.94 Xc or Xc = Xeq / 0.94 where Xeq (@ 6.6 kV' Base voltage.)

= Xeq = kV x kV x 1000 / (kVAR of Capacitor) = 53.66

Capacitive Reactance (Ohms/ph)

= Xc = 'Xeq / 0.94 = 57.09

Inductive Reactance (Ohms/ph)

Voltage across Equivalent circuit(Bus Voltage)

A

= VL = ICL x XL = 243.23

V

= 0.24

kV

= V = ICL x Xeq/1000 = 3.81

Capacitor Voltage

Ohms

= ICL = (Base voltage per phase) / Xeq = 71.01

Reactor Voltage drop for Current

Ohms

= XL = Xc x 6 % = 3.43

Current through the Equivalent circuit

Ohms

kV(Ph-N)

= Vc = V + VL = 4.05

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kV(Ph-N)

MV CAPACITOR SIZING CALCULATION FLSmidth Private Limited Project : Karaikal Port Project Phase -II (Stage-I) Customer : MARG Limited End User : MARG Karaikal Port Limited Consultant : HOWE India Private Limted

= 7.02

kV(Ph-Ph)

= 7.20

kV(Ph-Ph) Standard Rating

Capacitor shall be rated for above voltage to meet the reactor Voltage drop kVAR from Capacitor at above voltage

= Vc x ICL = Vc x Vc x 1000 / XC = 908.12

kVAR

Hence required capacitor rating

= 908.12

kVAR

Capacitor selected as per contract

= 1050.00

kVAR

Series reactor is Rated 6% of value of the Capacitor Finally selected

Hence Reactor value

= [(Capacitor Finally selected @ 7.2KV)/((7.2/6.6)2 x 0.940] x 0.06 49.76

New Xc

= V x V / MVAR = 49.37

Inductive Reactance XL (Ohms/ph)

kVAR at 6.6kV

Ohms

= 6% of new Xc = 2.96

Ohms

Hence, Net Impedance X'c

= Xc - XL = 46.41

Current at 7.2 kV (I)

= V / (1.732 x new Xc) = 84.2

Series Reactor Rating

Amps

= (I x I x XL) / 1000 = 20.99

Reactor Voltage Drop for Current

Ohms

kVAR

= I x XL = 249.232

V

= 0.249

kV

Conclusion :

Thus 1050 kVAR capacitor is sufficient for Bus-1 in 6.6 kV Switchboard at SS-1. This is a typical calculation and for Bus-2 in 6.6 kV Switchboard at SS-1,Bus-1 & 2 in 6.6 kV Switchboard at SS-2 capacitor size can be verified similarly. Capacitor value for Bus-1 in 6.6 kV Switchboard at SS-1

`= 1050 kVAR

(As per contract)

Capacitor value for Bus-2 in 6.6 kV Switchboard at SS-1

`= 1050 kVAR

(As per contract)

Capacitor value for Bus-1 in 6.6 kV Switchboard at SS-2

`= 650 kVAR

(As per contract)

Capacitor value for Bus-2 in 6.6 kV Switchboard at SS-2

`= 650 kVAR

(As per contract)

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