BK, BKD

Capacitor banks BK are designed for reactive power compensation in low voltage systems in industrial plants or branch stations.

Introduction

Low Voltage switchgear - BK, BKD - Capacitor banks

The transmission of reactive power in a power grid system reduces the quality of power grid parameters and increases payments for electricity. The ZPUE S.A. company provides solutions for inductive and capacitive reactive power compensation, such as:

  • capacitor banks,
  • capacitor banks with protective reactors,,
  • inductive banks (to be agreed with the manufacturer, after analysis of electrical grid parameters at the facility).

Reactive power compensation in an electric power system

There are three levels of reactive power compensation:

  1. Central compensation
    The bank is installed at the main switchgear (most frequent use).
  2. Group compensation
    The bank is installed at the sub-switchgear or near a group of consumers (wide cable grid, distributed consumers).
  3. Individual compensation
    Capacitors installed at individual consumers (high power consumers).
Reactive power compensation in an electric power system
Technical data of the capacitor battery
Rated power from 40 to 600 kvar 1)
Rated power per stage from 5 to 60 kvar
Number of compensation stages from 4 to 15
Rated operating voltage of the bank 400 V 2)
Rated insulation voltage 690 V 3)
Rated frequency 50 (60) Hz
Busbar rated short-time withstand current up to 40 kA
Ingress protection rating IP3X 4)
Cooperation with current transformers xx/5
Feeding in power supply cables from the top or from the bottom

Note:
1) The banks may be connected into bigger sets.
2) The banks may constructed in 500 V and 690 V versions.
3) In case of 690 V banks the insulation voltage is 750 V.
4) May be constructed up to IP54.

General principles for capacitor bay selection

The share of reactive power in total power consumption is determined by two coefficients. The first is the power coefficient cosφ, which is presented in the relationship (1.1)

1.1

The closer to one cosφ is, the smaller is the share of reactive power. Energy suppliers usually use power factor tgφ in their settlement contracts. A power factor tgφ was received from the relationship (1.2)

1.2

The closer to 0 tgφ is, the smaller is the transmission of reactive power. Based on the obtained tgφ and the demand for active power an approximate capacitor bank power may be obtained. The QBat bank power is established from the relationship (1.3)

1.3

Where tgφ — power factor required by the energy company.


Power and energy diagram

Power and energy diagram
P - active power [kW]
Ea - active energy [kWh]
Q - reactive power [kvar]
Er - reactive energy [kvarh]
S - apparent power [kVA]
Eopp - apparent energy [kvah]

Note!
For the correct selection of a capacitor bank it is necessary to perform electrical grid measurements at the facility.


Protecting the capacitor bank against adverse impact of harmonics.

The use of rectifiers, inverters and frequency converters in state of the art electricity consuming devices often causes deformation of voltage and current, which changes their waveform so that it is no longer a sine wave. They include numerous harmonics, which are an undesirable phenomenon, shortening the lifetime of electrical devices. This phenomenon is particularly dangerous in a capacitor bank. Capacitor reactance decreases when frequency increases, which results in a high intensity current flowing through the capacitor and destroying it. In order to protect the capacitor bank against adverse impact of harmonics, protective reactors connected in series with capacitors are used.

The degree to which distortions are present in the grid (the amount of harmonics) is specified by THD (Total Harmonic Distortion). The type of capacitor bank protection is selected depending on THD value.

THD  ≤ 15% Capacitor bank with normal capacitors (Un Kond = 400 V)
15% ≤ THD ≤ 25% Capacitor bank with heavy duty capacitors (Un Kond = 440 V)
25% ≤ THD ≤ 50% Capacitor banks with compensating reactors
THD > 50% Semiconductor-based tracking compensator

Capacitor banks made by ZPUE S.A. are identified by bank type symbol and enclosure type symbol

Capacitor banks made by ZPUE S.A. are identified by bank type symbol and enclosure type symbol

Bank type
BI Inductive bank
BK Normal capacitor bank (Un Kond = 400V)
BKW Heavy duty capacitor bank (Un Kond = 440V)
BKD7 Capacitor bank with reactors 7%
BKD14 Capacitor bank with reactors 14%
 
Enclosure type
R RN-W type enclosure
I INSTAL-BLOK type enclosure
Z ZR-W type enclosure
R - RN-W type enclosure
bk typ rn w
I - INSTAL-BLOK type enclosure
bk typ instal blok
Z - ZR-W type enclosure
bk typ zr w

Capacitor bank product range

Normal capacitor banks (Un capacitors 400 V)

Nominal bank
power [kvar]
Enclosure type Adjustment step Number of steps Example dimensions [mm]
[width x height x depth]
40 R 5 4 550 x 1275 x 400
45 R 5 4 550 x 1275 x 400
50 R 5 5 550 x 1275 x 400
55 R 5 4 550 x 1275 x 400
60 R / I 10 3 550 x 1275 x 400
70 R / I / Z 10 3 550 x 1275 x 400
80 R / I / Z 10 4 550 x 1275 x 400
90 R / I / Z 10 4 550 x 1275 x 400
100 R / I / Z 10 5 550 x 1275 x 400
110 R / I / Z 10 4 850 x 1275 x 400
120 R / I / Z 10 5 850 x 1275 x 400
140 I / Z 20 4 550 x 1950 x 400
160 I / Z 20 5 550 x 1950 x 400
180 I / Z 20 5 750 x 1950 x 400
200 I / Z 20 6 750 x 1950 x 400
220 I / Z 20 6 750 x 1950 x 400
240 I / Z 20 7 750 x 1950 x 400
260 I / Z 20 7 750 x 1950 x 400
280 Z 20 8 800 x 2200 x 600
300 Z 20 8 800 x 2200 x 600
320 Z 20 9 800 x 2200 x 600
340 Z 20 9 800 x 2200 x 600
360 Z 20 10 800 x 2200 x 600
380 Z 20 10 1000 x 2200 x 600
400 Z 20 11 1000 x 2200 x 600
420 Z 20 11 1000 x 2200 x 600
440 Z 20 12 1200 x 2200 x 600
460 Z 25 12 1200 x 2200 x 600
500 Z 25 11 1200 x 2200 x 600
550 Z 25 12 1200 x 2200 x 600
600 Z 25 13 1200 x 2200 x 600
We can manufacture a bank with different parameters at the customer's request.

Capacitor bank with reactors 7%

Nominal bank
power [kvar]
Enclosure type Adjustment step Number of steps Example dimensions [mm]
[width x height x depth]
40 R 5 4 850 x 1275 x 400
45 R 5 4 850 x 1275 x 400
50 R 5 4 850 x 1275 x 400
55 R 5 5 850 x 1275 x 400
60 R / I 5 5 850 x 1275 x 400
70 I 10 4 550 x 1950 x 400
80 I 10 4 550 x 1950 x 400
90 I 10 4 550 x 1950 x 400
100 I 10 5 550 x 1950 x 400
110 I 10 5 750 x 1950 x 400
120 I 10 5 750 x 1950 x 400
140 I 20 5 750 x 1950 x 400
160 I / Z 20 5 750 x 1950 x 400
180 Z 20 6 1000 x 2200 x 600
200 Z 20 6 1200 x 2200 x 600
220 Z 20 7 1200 x 2200 x 600
240 Z 20 7 1200 x 2200 x 600
260 Z 20 8 1200 x 2200 x 600
280 Z 20 9 1200 x 2200 x 600
300 Z 25 8 1200 x 2200 x 600
320 Z 25 8 1200 x 2200 x 600
340 Z 25 8 1200 x 2200 x 600
360 Z 25 9 2 x (800 x 2200 x 600)
380 Z 25 9 2 x (800 x 2200 x 600)
400 Z 25 10 2 x (800 x 2200 x 600)
420 Z 25 10 2 x (800 x 2200 x 600)
440 Z 25 11 2 x (800 x 2200 x 600)
460 Z 25 11 2 x (800 x 2200 x 600)
500 Z 25 12 2 x (1000 x 2200 x 600)
550 Z 25 13 2 x (1000 x 2200 x 600)
600 Z 25 14 2 x (1000 x 2200 x 600)
We can manufacture a bank with different parameters at the customer's request.

Capacitor bank with reactors 14%

Nominal bank
power [kvar]
Enclosure type Adjustment step Number of steps Example dimensions [mm]
[width x height x depth]
40 R 5 4 850 x 1275 x 400
45 R 5 4 850 x 1275 x 400
50 R 5 5 850 x 1275 x 400
55 R 5 5 850 x 1275 x 400
60 R / I 5 4 850 x 1275 x 400
70 I 10 4 550 x 1950 x 400
80 I 10 5 550 x 1950 x 400
90 I 10 4 550 x 1950 x 400
100 I 10 5 550 x 1950 x 400
110 I 10 4 750 x 1950 x 400
120 I 10 5 750 x 1950 x 400
140 I 20 5 750 x 1950 x 400
160 I / Z 20 6 750 x 1950 x 400
180 Z 20 6 1000 x 2200 x 600
200 Z 20 7 800 x 2200 x 600
220 Z 20 7 1200 x 2200 x 600
240 Z 20 8 1200 x 2200 x 600
260 Z 25 7 1200 x 2200 x 600
280 Z 25 8 1200 x 2200 x 600
300 Z 25 8 1200 x 2200 x 600
320 Z 25 9 1200 x 2200 x 600
340 Z 25 9 1200 x 2200 x 600
360 Z 25 10 2 x (800 x 2200 x 600)
380 Z 25 10 2 x (800 x 2200 x 600)
400 Z 25 11 2 x (800 x 2200 x 600)
420 Z 25 11 2 x (800 x 2200 x 600)
440 Z 25 12 2 x (800 x 2200 x 600)
460 Z 25 12 2 x (800 x 2200 x 600)
500 Z 25 13 2 x (1200 x 2200 x 600)
550 Z 25 14 2 x (1200 x 2200 x 600)
600 Z 25 16 2 x (1200 x 2200 x 600)
We can manufacture a bank with different parameters at the customer's request.

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