The essential use of power capacitor is to save power by improving PF of the system,one can save the penalty's electricity units & bills However harmonics are generated in the factories due to thyristorised switching / motors / AC-DC drives furnaces etc. The life of capacitor gets badly affected,as the power capacitor deteorates / fails due to this extra harmonic current ,the PF of the system gets affected. Need arises to change the power capacitor again & again. To avoid this one can use this harmonic filter reactor.
The use of this reactor not only saves the power capacitor but also enhances its life. The ultimate effect is continuous good PF sustention.
The similar effect can happen due to self resonant of the power capacitors with the system load there by creating adverse effects such as –
1) High voltage spike in the electrical field changing other components / instruments / appliances in the system.
2) Reduction in the capacitor life due to over loading.
3) Distortion in the electrical network.
4) Interference created due to these surges affecting computer, control system & other electrical/electronic appliances.
Approximate Winding Current Density: 1500-2000 Amps/Inch Squared Flux Density In Core: 1 – 1.3 Tesla.
Figure 1 – Above Picture Shows Typical Features of a Iron-Core Harmonic Filter Reactor
Winding
Copper / AI Wire,foil rectangular to reduce eddy current heating
Reactor Insulation
Class F/H on request
Reactor Temperature
90°C (Above 60°C Rise Ambient) h
Impregnation Process
Vacuum Pressure Impregnation
Impregnant
Epoxy or equivalent
Lamination
High-Grade Magnetic Steel
BIL & Voltage Rating
As required for the maximum system voltage
Taps
Provided as required
Gap Design
Distributed and cemented to reduce noise
The reactor current ratings are typically based on the following considerations:
• The reactor core will not saturate for currents less than 170-250% of the fundamental current rating of the reactor.
• Peak flux density of the shall be less than 1.2 – 1.4 Tesla assuming all harmonic current peaks are 100% coincident (Core design is not based on RMS current rating of reactor)
• When specific harmonic current data and system impedance data are provided, the reactor current spectrum will be based upon computer simulations and an engineering margin.
Common Features :-
• 4 – quadrant measurement of reactive and constant supervision of inductive/capacitive load
• Measurement and supervision of each step of kvar output during switching process
• Adjustment of current transformer ratio for control purposes is not required. (On BLR-Cm, input of the CT ration is required for the indication of values measured.)
• Adjustment of target cos phi in the range 0.70 (lag) – 1 – 0.90 (lead)
• Adjustable switching time
• No-volt release with power interruption greater than 35 ms.
• 90 second lockout time following power failure and subsequent power restoration.
• Optical (LED) indication of each individual stage
• Failure alarm if target cos F is not achieved (after completion of 75 switching cycles)
• Failure alarm if relay detects there is a risk of overloading capacitors due to excessive harmonic current
