Department of Mechanical Engineering HumilityEntrepreneurshipTeamwork LearningSocial ResponsibilityRespect for Individual Deliver The Promise BS&H, GMR Institute of Technology, Rajam Page -1 How to Select a Capacitor Banks – Constant/Linear/Non Linear load: Industry Follow Methods

Department of Mechanical Engineering HumilityEntrepreneurshipTeamwork LearningSocial ResponsibilityRespect for Individual Deliver The Promise GMR Institute of Technology, Rajam What is power factor ?

Department of Mechanical Engineering HumilityEntrepreneurshipTeamwork LearningSocial ResponsibilityRespect for Individual Deliver The Promise GMR Institute of Technology, Rajam 3 13-Aug-15 How it affects the system?

Department of Mechanical Engineering HumilityEntrepreneurshipTeamwork LearningSocial ResponsibilityRespect for Individual Deliver The Promise GMR Institute of Technology, Rajam 4 13-Aug-15 Any Analogy in Practical Perspective?

Department of Mechanical Engineering HumilityEntrepreneurshipTeamwork LearningSocial ResponsibilityRespect for Individual Deliver The Promise GMR Institute of Technology, Rajam 5 13-Aug-15 Any Analogy in Much Simpler way?

Department of Mechanical Engineering HumilityEntrepreneurshipTeamwork LearningSocial ResponsibilityRespect for Individual Deliver The Promise GMR Institute of Technology, Rajam (1) Fixed type capacitor banks The reactive power supplied by the fixed capacitor bank is constant irrespective of any variations in the power factor and the load of the receivers. These capacitor banks are switched on either manually (circuit breaker/ switch) or semi automatically by a remote-controlled contactor. This arrangement uses one or more capacitor to provide a constant level of compensation. These capacitors are applied at the terminals of inductive loads (mainly motors), at bus bars Disadvantage: Manual ON/OFF operation. Not meet the require kvar under varying loads. Penalty by electricity authority. Power factor also varies as a function of the load requirements so it is difficult to maintain a consistent power factor by use of Fixed Compensation i.e. fixed capacitors. Fixed Capacitor may provide leading power factor under light load conditions, Due to This result in over voltages, saturation of transformers, mal-operation of diesel generating sets, penalties by electric supply authorities.

Department of Mechanical Engineering HumilityEntrepreneurshipTeamwork LearningSocial ResponsibilityRespect for Individual Deliver The Promise GMR Institute of Technology, Rajam 7 13-Aug-15

Department of Mechanical Engineering HumilityEntrepreneurshipTeamwork LearningSocial ResponsibilityRespect for Individual Deliver The Promise GMR Institute of Technology, Rajam 8 13-Aug-15 Then, Where should we use? Application: Where the load factor is reasonably constant. Electrical installations with constant load operating 24 hours a day Reactive compensation of transformers. Individual compensation of motors. Where the kvar rating of the capacitors is less than, or equal to 15% of the supply transformer rating, a fixed value of compensation is appropriate. Size of Fixed Capacitor bank Qc ≤ 15% kVA transformer

Department of Mechanical Engineering HumilityEntrepreneurshipTeamwork LearningSocial ResponsibilityRespect for Individual Deliver The Promise GMR Institute of Technology, Rajam Automatic type capacitor banks: The reactive power supplied by the capacitor bank can be adjusted according to variations in the power factor and the load of the receivers. These capacitor banks are made up of a combination of capacitor steps (step = capacitor + contactor) connected in parallel. Switching on and off of all or part of the capacitor bank is controlled by an integrated power factor controller. The equipment is applied at points in an installation where the active-power or reactive power Variations are relatively large, for example: At the bus bars of a main distribution switch-board, At the terminals of a heavily-loaded feeder cable. Where the kvar rating of the capacitors is less than, or equal to 15% of the supply transformer rating, a fixed value of compensation is appropriate. Above the 15% level, it is advisable to install an automatically-controlled bank of capacitors. Control is usually provided by contactors. For compensation of highly fluctuating loads, fast and highly repetitive connection of capacitors is necessary, and static switches must be used.

Department of Mechanical Engineering HumilityEntrepreneurshipTeamwork LearningSocial ResponsibilityRespect for Individual Deliver The Promise GMR Institute of Technology, Rajam MethodAdvantagesDisadvantages Individual capacitors Most technically efficient, most flexible Higher installation & maintenance cost Fixed bankMost economical, fewer installations Less flexible, requires switches and/or circuit breakers Automatic bank Best for variable loads, prevents over voltages, low installation cost Higher equipment cost CombinationMost practical for larger numbers of motors Least flexible

Department of Mechanical Engineering HumilityEntrepreneurshipTeamwork LearningSocial ResponsibilityRespect for Individual Deliver The Promise GMR Institute of Technology, Rajam Aug-15 System VoltageMinimum rating of capacitor bank 3.3 KV, 6.6KV75 Kvar 11 KV200 Kvar 22 KV400 Kvar 33 KV600 Kvar Selecting Size of Capacitor Bank: The size of the inductive load is large enough to select the minimum size of capacitors that is practical. For HT capacitors the minimum ratings that are practical are as follows:

Department of Mechanical Engineering HumilityEntrepreneurshipTeamwork LearningSocial ResponsibilityRespect for Individual Deliver The Promise GMR Institute of Technology, Rajam Aug Selection of Capacitor as per Non Liner Load: 2. Effect of series and Parallel Connection of capacitor: 3. Can we connect the capacitors in delta? Then what is its effect? 4.Can we connect the capacitors in star connection? Then what is its effect? 5. Can we connect the capacitors in star connection with ground? Then what is its effect?

Department of Mechanical Engineering HumilityEntrepreneurshipTeamwork LearningSocial ResponsibilityRespect for Individual Deliver The Promise GMR Institute of Technology, Rajam Aug-15 Placement of Power Capacitor Bank for Motor: Location 1 (The line side of the starter): Then what will happen? Location 2 (Between the overload relay and the starter): Then what will happen? Location 3(The motor side of the overload relay):Then what will happen?