Special Features || Electrical Parameters || Power Capacitor Box Dimensions || Selection of Power Capacitors || Instruction for Installation & Maintenance || Important factors || Cause of Failure || Installation & Operation || Guidelines for Installation & Operation || Distributing Capacitors Across Major Load Points

Why a Power Capacitor is needed
Conservation of Energy due to LT Shunt Capacitors is an established fact. Needless to say that these Capacitors have contributed significantly in Electrical Installations by way of reduction in KVA demand for specific KW Loads, thereby saving on electricity Bills. Higher Capacity utilisation of Transformers, connecting cables and switchgears are direct saving for given specific load. These capacitors are also useful in system voltage stabilisation and distribution.

SARDA Power Capacitors are manufactured in controlled atmosphere and with modern technology to improve Power factor of Electrical Installation of all kinds of industries and in agriculture pumpsets. The Capacitors are made of Heavy edge zinc alloy metallised PP film and dry construction.

ADVANTAGE OF USING POWER CAPACITORS:
To increase the efficiency of the electrical system, power factor is improved by providing power capacitors in the electrical system. Some of the major advantages of using power Capacitor are :-

• Reduction in Electricity bill.
• Reduction of power losses.
• Improvement in Voltage regulation.
• Meet statutory requirement & avoid penalty.

CONFIGURATION HIGHLIGHTS :
	Advanced vapour coating techniques involving high degree of purity of metal, coupled with heavy edge gives added advantages to metallised Polypropylene film of self healing type to handle higher currents and withstand the electrical surges that are predominantly observed in the Power systems.
	Effects of harmonic currents are minimized by using suitable filter networks in conjunction with these Capacitors which can be supplied on specific request.
	I n rush current limiting coils are used for longer life of Capacitors.
	Low energy consumption due to low watt losses i.e. , <0.5 watt/KVAr.
	Higher insulation properties and temperature withstanding Capability.
	Modular design : For easy maintenance as the modules are replaceable.
	Explosion Proof Design : By using soft Epoxy / PU Resin, pressure developed due to any internal fault of the Capacitor will disconnect the electrical connection of the module and safe guard the nearby equipment.
	Box (Housing) for Capacitor is provided with Louvers for free air ventilation thereby keeping operating temperature at lower levels and increasing life of the Capacitors.
	KVAr ratings are from 1 KVAr to 50 KVAr. Banking of KVAr units is also undertaken by us for higher KVAr ratings requirements.
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TYPES:           STANDARD        HEAVY DUTY         DOUBLE DIELECTRIC       ALUMINIUM CYLINDRICAL

STANDARD TYPE
These Capacitors are light weight and compact in size have been designed keeping in view, the normal duty cycle present in various utilities. These Capacitors are used for almost constant loads having negligible variations.
HEAVY DUTY TYPE
These Capacitors have been designed to suit fluctuating load conditions and withstand over-voltage and over-currents within permissible limits. These Capacitors are stronger than standard type to withstand required dielectric stress which varies non-linearly.
DOUBLE DIELECTRIC TYPE
Aiming at replacing the conventional mixed dielectric oil type capacitors, our double dielectric type is designed to suit continuous operation for heavy duty application particularly where presence of harmonics plays a prominent role. These Capacitors are mechanically robust and electrically stable to withstand combined effects of thermal and electrical stresses prevalent in major industries.
ALUMINIUM CYLINDRICAL TYPE
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	SPECIAL FEATURES
	ISI marked
	Approved by various State Electricity Boards.
	Self Healing MPP Film with Heavy Edge Metallization.
	Manufactured with latest state of art technology
	High Insulation Resistance
	Low Losses and longer life
	Dry Construction
	Burst-proof modules.
	Compact Size
	Better power handling capacity
	With/without inductor coil
	Non-modular / modular construction
	Multiple modules per rated output
	Quality system ISO:9001-2000
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ELECTRICAL PARAMETERS:
Sl.No.	Electrical Characteristics	Standard	Heavy Duty	Double Dielectric	Aliminium Cylindrical
1	Rated Voltage (VAC)	250 / 415 / 440	415 / 440	415 / 440	400/440
2	Max Over Voltage (Max 8Hrs per day)	1.1 Rated	1.2 Rated	1.3 Rated Volt	1.3 Rated Volt
3	Max. Over Current	1.3 Rated	1.4 Rated	1.6 Rated	1.3 Rated
4	Rated Frequency (Hz)	50	50	50	50
5	Capacitance Tolerance	-5% to + 10%	-5% to + 10%	-5% to + 10%	-5% to + 10%
6	Temperature Category	-5 C to 50 C	-5 C to 50 C	-5 C to 50 C	-5 C to 50 C
7	Losses (Watts per/KVAr)	0.5 to 0.8	0.5 to 0.8	0.5 to 0.8	0.5 to 0.8
8	Max. Ambient Temp.	50 C	50 C	50 C	50 C
9	Max. Avg. Temp. Over 24 Hrs	40 C	40 C	40 C	40 C
10	Max. Avg. Temp. Over 1 Year	30 C	30 C	30 C	30 C
11	Internal Connection	Single Phase Three Phase Delta	Three Phase Delta	Three Phase Delta	Single Phase ThreePhase Delta
12	Application	Indoor	Indoor	Indoor	Indoor
13	Insulation Level (KVAC)	3/-	3/-	3/-	3/-
14	Discharge Device	External	External	External	External
15	Ref. Standard IS:	13340-1993-1334-1992
16	Ref. Standard IEC	60831-1(2002)

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POWER CAPACITOR BOX DIMENSIONS (in mm)

Rated KVAr	STANDARD TYPE			HEAVY DUTY			DOUBLE DIELECTRIC
	Length	Width	Height	Length	Width	Height	Length	Width	Height
1	105	40	130	120	45	165	170	60	245
2	145	50	170	150	55	205	180	65	265
3	145	50	170	150	55	205	190	65	295
4	145	50	170	180	65	315	215	75	295
5	175	60	205	180	65	315	215	75	420
6	175	60	205	180	65	315	215	75	420
7	175	60	205	210	75	315	215	75	420
8	175	60	205	210	75	315	215	150	420
9	210	70	235	210	75	315	215	150	420
10	210	70	235	220	80	425	270	200	465
12	210	70	235	220	80	425	270	200	465
12.5	210	70	235	220	80	425	270	200	465
15	235	160	240	220	80	425	270	270	465
20	235	160	240	250	170	390	375	375	485
25	235	160	240	250	170	390	375	375	485

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Selection of Power Capacitors

With the advancement of Technology in the Capacitor field, new designs to suit common industrial and agricultural requirements including that of Rolling Mills, Induction Furnaces, Thyristor controlled Drivers both AC & DC) Heavy presses, Rectifiers, Advance welding system and other such loads, have been developed.

Standard	Heavy Duty	Double Dielectric
Utilities having steady uniform inductive loads like	Utilities having variable inductive loads and with total harmonic distortion not exceeding 5% like medium scale industries	Utilities having variable and fluctuating inductive loads and with total harmonic distortion not exceeding 8% like
Agricultural pump sets	Garment industries	Steel Rolling mills
Commercial establishments	Fabrications	Cement Industries
Small scale Industries etc.,	Welding shops	Textiles
	Machine shop & Tool	Heavy chemical industries
	Room	Pharmaceutical industries
	Steel wire drawings	Sugar plants
	Bakeries	Automobile plants
	Floor mills	Paper industries
	Coffee curing works	Agro product industries
	Control Panels	Food processing plants
	Oil mills	Granites & Stone polishing units
	Steel melting	Animal feed industries
	Glass industries	Wind mills
		Heavy welding equipments
		Power Frequency induction furnaces
		Steel Melting industries etc.

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INSTRUCTION FOR INSTALLATION & MAINTENANCE OF L.T. POWER CAPACITORS.
	Ensure proper rating of KVAr required is connected at load points.
	Adequate rating of fuse / cable / switch gears shall be used.
	Firm fixing of capacitors along with cable lugs of appropriate size shall be used.
	Earthing should be done properly to avoid accidental leakage current.
	Repeated switching without sufficient time delay shall be avoided.
	Discharge resistor needs periodic checking in order to avoid shock hazards.
	Periodic checking of current in each phase is essential to keep track of capacitor condition.
	Switch off power capacitors under light load or no load conditions.
	All capacitors must be discharged before handling.
	Harmonic filter must be provided if presence of Harmonics, is significantly predominant.
	Avoid transient over voltages/surge current by using suitable protective devices.
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Important factors which influence quality and reliability of power factor correction capacitors at end users place
	Immediately after receipt please check the Capacitor and ensure that they are in good condition without any external damages during transit.
	Please ensure that the Capacitor terminals are not loosened due to any reason while connecting to the load. Any loose contact at the terminals may result in heating and premature failure of Capacitors.
	Ensure proper grounding of Capacitor before energising it.
	Check discharge resistors connected across the terminals are intact, Capacitors must be discharged fully before handling it.
	Energise the Capacitor and measure voltage & current using a clamp meter in all the phases.
	Proper current rating MCB/MCCB is recommended in order to avoid over current to the Capacitor which may cause fire risk.
	Automatic switching of power Capacitor in sequence shall be such that already energised Capacitor shall have sufficient time delay circuit for discharge before it is subjected to another re-striking operation. This is an important aspect, which if proper care is not taken may result in over-voltage condition, increasing the risk of Capacitor being subjected to high voltage stress level and there by the dielectric insulation breakdown.
	Harmonic distortions in Electrical Systems are commonly present in loads like thyristor controlled D.C drives, rectifiers, Arc welding machines, etc. Harmonic Filters reduce harmonic distortion to avoid higher current across the Capacitor terminals resulting in over heating the Capacitor.
	Switch 'Off' Capacitors when inductive loads are in use. Care must be taken to see that the Capacitors shall not draw any current from the source which results in leading power factor which is not recommended since the reactive power compensation exceeds more than what is needed.
	When star delta starters for higher rating inductive motors are switched on, take care so that Capacitors are switched on when motors are running in delta connection only. This can be done by making use of delay timer which can switch on the contactor and Capacitor is in the circuit.
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CAUSES OF FAILURE
	Loose contact due to improper cable termination. Improper selection of Cable Size & Lugs.
	Protective devices like MCB / MCCB, fuses are bypassed while giving connections to Capacitors selecting high rated protective devices for Capacitors.
	High ambient temperatures exceeding 55 degree C.
	Deposition of Carbon / Metallic dust at the terminals of Capacitors.
	Connecting Capacitor units / Banks at the Busbar, when the Inductive load conditions are low without any switching arrangement.
	Switch off Capacitors suitably according to inductive load utilization.
	Using Capacitors
	Selecting wrong type Capacitors where load conditions are fluctuating due to frequent switching operations.
	Do not discharge Capacitors by directly short circuiting the top terminals (R.YB) of the Capacitor. It should be done through a discharge resistor only. Capacitor's life gets reduced if discharge is done directly.
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INSTALLATION & OPERATION
INTRODUCTION :
Due to following types of inductive loads the efficiency of the electrical system reduces.
	Transformer
	Induction motor
	Induction furnace
	Welding machine
	D.C. motor
	Voltage regulator
	Discharge lamps etc.,
To increase the efficiency of the electrical system, power factor should be improved by introducing power capacitors in the electrical system. Some of the major advantages of improving power factor are:
	Reduction in Electricity bill
	Improved voltage level in system
	Reduction in system losses
If power capacitors are connected at main bus bar i.e., at one point, the advantage of reduced system losses and improved voltage level cannot be taken fully. To get maximum advantage of above mentioned three points, Power capacitors should be distributed and connected to individual inductive loads preferably or else distributed at major load centers.
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Guidelines for Installation & Operation
	Unlike most electrical apparatus, shunt power capacitors whenever energized, operate continuously at full load or at loads that deviate as a result of voltage and frequency variations. Over stressing and over heating shorten the life of a Capacitor and therefore the operating conditions that is temperature, voltage and current should be strictly controlled.
	When a Power Capacitor is permanently connected to a motor, difficulties may arise after disconnecting the motor from the supply. The motor while still revolving , may act as a generator by self excitation and may give rise to voltages considerably in excess of the system voltage. This however, can be prevented by ensuring that the Capacitor current is less than the magnetizing current of the motor ; a value of about 90% is suggested.
	When a Power Capacitor is connected to a motor associated with Star Delta starter, care should be taken so that no overvoltage can occur during the operation of the starter. Capacitor should be switched 'ON' when the motor is running in delta connection only.
	Avoid loose connections. Any bad contact in Capacitor circuits may give rise to arcing, causing high frequency oscillations that may overheat and overstress the Capacitors. Regular inspection of Capacitor connections is recommended.
	Ensure proper grounding of Capacitor before energisation.
	Capacitor units are provided with discharge resistors to reduce the residual voltage from the crest value of the rated voltage to 50V or less within one minute. A discharge device is not a substitute for short circuiting the Capacitor terminals together and to earth before handling. Do not energise the Capacitors without discharge resistors. Automatic switching of Capacitors in APFC panels or otherwise should be such that energized Capacitor will have sufficient time delay circuit for discharging fully before being subjected to another restricting operation. This is very important and if proper care is not taken may result in over voltage condition which may lead to dielectric insulation breakdown.
	Connect Capacitors with inductive load such that when inductive is load is 'ON' then only the Capacitor is 'ON'. Do not energise Capacitors under light load conditions. Select proper rating of Capacitor to be used with the Inductive load as per the guidelines given.
	Capacitors should never be operated with currents exceeding the maximum valve of 1.30 times the current that occurs at rated sinusoidal voltage and rated frequency excluding transients . Overload currents may be caused either by excessive voltage at the fundamental frequency or by 'harmonics' The chief sources of harmonics are (A) Rectifiers (B) Arc furnaces (C) Thyristor controlled drives (D) Saturated transformer cores
	Do not discharge Capacitors by directly short circuiting the top terminals (R.YB) of the Capacitor. It should be done through a discharge resistor only. Capacitor's life gets reduced if discharge is done directly. The reactance of the Capacitor is inversely proportional to the frequency. Hence, if the applied voltage includes components having frequencies higher than the fundamental frequency, then the current drawn by the Capacitor will be greater than would be produced by the same voltage at the fundamental frequency. If harmonics are present in the system, then it is necessary to carry out harmonic analysis and based on data connect proper rating of Harmonic filter.
	Capacitors should be installed so that there is good air circulation around it.
	Select Capacitors with proper rated voltage. The rated voltage of the Capacitor should be equal to the service voltage of the network to which Capacitor is connected. It should be noted that service voltage of the network will be higher at night times than during day time. Capacitors may be subjected to high overvoltages due to lightening and other reasons. Properly rated switching and protective devices should be used to regulate over voltages.
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Distributing Capacitors Across Major Load Points
	Power Transformer :
	Capacitors are connected for transformer as transformer itself has to be considered as a continuous inductive load. Magnetising current for generation of flux in the core lags 90° to the applied voltage. Capacitors required for full load transformer = Percentage impedance x KVA of transformer / 100 As no load magnetizing current of transformer is almost 50% of full load magnetizing current, Capacitors required has to break in two parts. 50% KVAr rating should be 'ON' when transformer is loaded & should be switched 'OFF' during no load condition.
	Welding Transformer :
	Welding transformers are of two types namely :-
	(A) Two Phase welding transformer (B) Three Phase welding transformer
	Two phase weldingTransformer :
	The KVAr rating of Capacitor should be around 50% of the continuous KVA rating of the transformer.
	Three phase weldingTransformer :
	The KVAr rating of Capacitor should be around 33% of the continuous KVA rating.
	INDUCTION MOTOR
	Capacitors should be connected to reduce the magnetizing current of motor which depends on HP rating and rpm of motor.
	With DOL STARTER
	Connect Capacitor between overload relay and motor for reduced starter current. By this overload current setting is reduced.
	With STAR DELTA STARTER
	Connect Capacitor when motor is in delta connection. The Capacitor rating should correspond approximately to the apparent power of the motor on no load.
	D.C. MOTOR
	In D.C. motor, power factor depends on firing angle (á) and varies according to it. Power factor of D.C. motor will be approximately 0.6 lag. Hence, connect Capacitors approximately equal to the KW rating of the motor. Generally, D.C. motor generates harmonics of higher frequencies which are multiples of fundamental frequency (50 Hz) Capacitors have to carry current more than the rated current and therefore harmonic filters have to be installed. Also select more number of Capacitors will lesser rating than selecting a single Capacitor bank or of higher rating KVAr so that heat dissipation will increase and reduced chances of thermal runaway.
	Connecting Capacitors individually to individual inductive load is more dependable system to solve low power factor and thereby precious power can be saved. It is also bonus to the utility.
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