A wide range of Capacitor units is available complying with relevant IS Specifications. The voltage of a capacitor unit can be selected from 660 V to 33 KV. The great number of different voltage ratings which can be supplied enables a wide variety of needs to be met. This flexibility is advantageous when series parallel combinations are required for high power bank arrangements.
In general, external fuses are recommended. Either expulsion type or H.R.C. type fuses are mounted adjacent to a live bushing terminal. It is suggested that details of service requirements and the nature of the installation should be given to enable to indicate the fuse type and characteristics most appropriate.
Resistors of suitable ratings are fitted to each Capacitor unit and the maximum discharge time for all ratings is five minutes.
Dry assembly is done under strict supervision to ensure rope construction of capacitors. Ceramic insulators are fitted on the containers using silicon rubber seal to ensure 100% leak proofness. Containers are pressure tested.
Capacitor units are fitted with one or two bushings depending on the application; and the main insulation to the container is graded accordingly.
CAPACITOR BANK CONSTRUCTION
Capacitor banks can be supplied for any desired level of reactive power voltage rating. The assembly of capacitor units into banks can be facilitated by using prefabricated steel structure supplied on request. The complete rack assemblies can quickly be built into a stack at site by means of a mobile crane or similar equipment, once the relatively simple foundations have been prepared.
PROTECTION OF CAPACITOR BANKS
It is desirable to provide safeguards for capacitor banks is addition to the fuse protecting the individual capacitor units. Economic considerations determine which of the several form should be used; the preferred methods are fundamentally balanced circuit systems giving indication of disconnections due to faults within the bank. Although in many cases out-of-balance conditions can be withstood safely for short period, it is advisable to restore the bank to normal working as quickly as possible. For medium size and large banks from about 600 KVAr upwards, the use of damping devices is necessary for the parallel switching of a number of capacitor circuits. This reduces the stressing of the capacitors and switchgear and also prevents reactions on the network.
INFORMATION REQUIRED WITH ENQUIRY
To design the most suitable capacitor to suit your requirement, it is necessary to have all relevant details of the installation or system to which the capacitors are to be applied. For instance, equipment’s such as rectifiers, arc furnace or transformer (under certain conditions) produce harmonics, necessitating special considerations. Therefore, following information should accompany any enquiry:
- The main purpose for which capacitors are being considered, e.g., Increased KW transmission on a line, reduced voltage drops on a line; decreased Power loss on a line, increased transformer capacity, increased alternator capacity, etc.
- Output in KVAr or load details like KVA load, present power factor and power factor required.
- System voltage, frequency and number of phases.
- State whether any abnormal voltage rises are expected. If yes, what is the highest Voltage expected.
- State whether waveform is sinusoidal or whether harmonic voltages are present. If harmonics are present give Percentage voltage for each harmonic frequency.
- RInsulation voltage required, if different from the line voltage.
- Type and details of load, preferably give a simple schematic diagram.
- Proposed location of capacitors Indoors / outdoors.
- Ambient temperature -peak value and average over 24 hours.
- Any other relevant details.
Capacitance: to 200 KVAr
Voltage: Up to 33 KV
Phase: Single or Three
Frequency: 50 Hz/ 60 Hz