Low Voltage Capacitors
 
 

Low Voltage Capacitors

 

Low Voltage Film Foil (APP) Capacitors

Features
• Bi-axially oriented both side hazy(rough) polypropylene
   film to ensure good oil impregnation
• Capacitor grade aluminum foil for high current
   carrying capacity
• No reduce in output
• Low Losses < 0.3 watts per kVAr
• Suitable for flexi banking
• High peak inrush current withstand capability
• Specially vacuum processed, oil impregnated design
• Suitable for frequent switching operation

Applicable standards

IS 13585 (Part 1) : 2012 IEC 60931-1 :1998 1Ø/3Ø APP (Film + Foil) type Heavy Duty Capacitor for Power Factor Improvement& Harmonic Filtering.

Low voltage capacitors
Principles of Power Factor Correction
A vast majority of electrical loads in low voltage industrial installations are inductive in nature. Typical examples are motors, transformers, drives & fluorescent lighting. Such loads consume both active and reactive power.
The active power is used by the load to meet its real output requirements whereas reactive power is used to meet its magnetic field requirements.
The reactive power (inductive) is always 90° lagging with respect to active power as shown in figure 1. Figure 2 & 3 show the flow of kW, kVAr and kVA in a network before and after installation of Capacitors.
Active and Reactive power always flow in every electrical installation. This means that the supply system has to be capable of supplying both active and reactive power.
The supply of reactive power from the system results in reduced efficiency due to
• Increased current flow for a given load
• Higher voltage drops in the system
• Increase in the losses of Transformers, Switchgear and Cables
• Higher KVA demand from supply system as given in figure 2
• Higher electricity cost due to levy of penalties / loss of incentives
 

It is therefore necessary to reduce & manage the flow of reactive power to achieve higher efficiency of the electrical system and reduction in cost of electricity consumed. The quick & cost effective method of reducing and managing reactive power is through improvement of power factor by
installing Power Capacitors. Concept of reduction in kVA demand from the system is shown in figure 3.

Application
PF correction in LV network
LV Dynamic Automatic power factor
correction panels (APFC) (Contactor /
Thyristor switched)
Fixed power factor correction
Tuned and detuned Harmonic filters
 

Safety
Internal element fuse design Non polluting, nonhazardous NPCB Capacitor fluid Externally fitted Discharge resistors Steel enclosure for protection from live terminals

Standard ratings of Capacitors
Output: 5, 7.5, 10, 12.5, 15,20,25 KVAr / 41 S and 440 Volts with 151 and CE marking Higher ratings can be supplied on request.

Effect of temperature rise
Every Capacitor is designed for a specific lowest and highest ambient temperature. Life of Capacitor decreases when operated beyond the limits. Capacitor should not be exposed to heat and must be kept in a well- ventilated position to avoid overheating. Capacitors used in conjunction with series reactor in detuned filter application, the location of reactor affects the surrounding air temperature, Since the reactor radiates heat, it should be placed always above the Capacitor or in a separate column in order to protect capacitors from excessive heating. It is always recommended to adopt forced air cooling in detuned reactor filter panels.
 
Low voltage capacitors
 
Effect of over current
The maximum allowed RMS current is given in technical data ofthe Capacitor. Operating the Capacitor beyond, will reduce the life of
the Capacitor. Higher current drawn by Capacitor means increased losses. This results in heating of the Capacitor, thereby, reducing
its life.

Effect of over voltage
Operating the Capacitor beyond permissible limits of over voltage will damage the Capacitor. Some levels of over voltages are accepted only for a short duration but they reduce the life of the Capacitor. Such levels must not occur for more than 200 times in the life time of a Capacitor.
 
Protection of Capacitors
Capacitors have to be protected against short circuit currents by using external fuses having adequate current rating. It is recommended to use HRC fuses, having current rating of 2 -2.5 times the rated current of Capacitor.

Switching of Capacitors
When the Capacitor is switched in to the network, high inrush currents flow. Fast acting contactors which are capable of handling the high current level should be used. Capacitor duty contactors (connected with resistors) are better suited, since they damp the inrush currents. Contactor / switch gear ratings should be minimum 1.5 times of the rated current of Capacitors.

Discharging Capacitors
Capacitor must be discharged before it is re-energized to avoid superimposition of voltage over residual voltage. This helps to increase the life of Capacitor. The Capacitor voltage must reduce to less than 75V within 3 minutes. This is achieved by connecting an external discharge resistor
across the Capacitor terminals. No disconnecting device be connected between the Capacitor and discharge resistor.

Earthing of Capacitor
An Earthing terminal has been provided on the body of the Capacitor to be used for earthing. It is recommended to earth the Capacitor for safety purpose.

Resonance
Capacitors connected in harmonic rich environment are prone to resonance related problems, leading to failure of Capacitors. Under such conditions detuned reactors in series with Capacitors are preferred.

Maintenance
The Capacitors should be kept in a well- ventilated area, free from any corrosive medium. Terminal connections should be tightened as recommended and cleaned regularly for better performance and enhanced life
 

De-tuned Harmonic Reactor
Iron Cored Reactors are used along with Capacitors in De-tuned harmonic filter applications.

Rating
Detuned Reactors are available in 5%, 6%, 7% and 14 % ratings.

Features
• Linearity up to 200%
• Compact size and convenient mounting
• Low losses
• Low noise level
• Tested as per IS 5553 and IEC 60076 - 6 Safety
• Thermal switch provided to protect the Reactor from overheating.
• E class insulation

De-tuned Harmonic Reactor
Feedabck
 
MAGNEWIN ENERGY PVT. LTD.
MAGNEWIN ENERGY PVT. LTD.
Plot No. K-2, MIDC, Kupwad,
Dist. Sangli - 416436,
Maharashtra, INDIA.
Tel. No.: +91-233-2645641, 2645642,
2645141, 5644456
Fax No. : +91-233-2645856,
Cell : +91 - 94230 02258

 
 
   
Visit also at
www.watercooledcapacitors.net, www.furnacedutycapacitors.net, www.energystoragecapacitors.net, www.lowinductancecapacitors.net, www.harmonicfilters.co.in, www.surgecapacitors.in, www.pulsedischargecapacitors.net