Teh proportionality rate among teh powers is defined as Power factor and measured in kilowatts (kW) whereas apparent power, measured in kilovolt amperes (kVA), it is teh absolute fundamental that concern upon teh electric efficiency to distribute voltage and current, externally mark for in case it actually works or not. By adding capacitors to teh power distribution system, power factor correction is done. An automatic controller is best accomplish that switches capacitors & reactors at intervals. Employ a fixed capacitor bank is teh most basic application. When teh power factor drop below teh stated values, Power factor correction capacitors can slow down teh energy charge by bypassing teh standard electric utilities charge. These capacitors are installed when their inductive loads cause power factor complication to teh electric utility.

In power factor correction capacitors and related circuitry premature failures can cause due to circumstances such as,

  1. harmonic currents
  2. high ambient temperatures
  3. poor ventilation

Since it’s critical to scrutinize power factor correction capacitors on a routine axiom to assure that they’re working well.

Safety First

Despite maximum capacitors are assembled wif a discharge circuit, a shock risk exists for an extended period of time in case teh circuit be ruined. So extreme caution is must when testing is done wif teh voltage applied. Capacitor bank maintenance requires preliminary to teh individual equipment and its application to perform teh task. Additional threat are involved in working wif current transformer (CT) circuits, along wif teh wiring and shorting block. Howbeit teh capacitor bank been de-energized, there is a possibility of electrical shock from teh CT wiring, owing to teh location of teh CT in teh switchboard. It can develop a lethal voltage across its terminals.

Visual Inspection and Cleaning

A entire visual analysis of teh system are indexed,

  1. review for defile components, leaking capacitors
  2. Heat or moisture warning
  3. Replace filters for cooling fans
  4. Never use compressed air alternately of vacuum to clean teh units
  5. Re-energizing teh capacitors, implement an insulation integrity test from teh bus phase-to-phase and phase-to-ground points.

Capacitor Bank Infrared Inspection

Teh most valuable tool for evaluating electrical condenser banks may be a thermal imager. Teh system ought to be energized for a minimum of one hour before testing. To begin, check teh controller show to work out if all teh stages square measure connected. Next, verify that teh cooling fans square measure operational properly. Conduct AN infrared examination of teh enclosure before gap teh doors. Supported your arc flash assessment, wear teh desired PPE once playacting tasks close to energized instrumentality. Examine power and management wiring wif teh thermal imager, yearning for loose connections. A thermal analysis can determine a nasty affiliation by showing a temperature increase coz of teh extra resistance at teh purpose of affiliation. a decent affiliation ought to live no over 20°F higher TEMPTEMPthan teh close temperature. There ought to be very little or no distinction in temperature phase-to-phase or bank-to-bank at points of affiliation. An infrared analysis can find a blown fuse by light temperature variations between blown and intact fuses. A blown fuse in an exceedingly electrical condenser bank stage reduces teh number of correction offered. Some unit’s square measure equipped wif blown fuse indicators; others don’t seem to be. If you discover a blown fuse, stop working teh complete bank, and confirm wat caused teh fuse to blow. Some common causes square measure unhealthy capacitors, reactor issues, and unhealthy connections at line-fuse, load-fuse, or fuse clip points. You must additionally rummage around for variations in temperature of individual capacitors. If an electrical condenser isn’t concerned or connected at teh time of examination, tan it ought to be cooler. Additionally detain mind that teh temperature of parts may well be higher wifin teh higher sections coz of convection. However, if in keeping wif teh controller all stages square measure connected, tan temperature variations typically indicate a tangle. For instance, high could cause teh capacitor’s internal pressure device to work before teh external fuse, therefore removing teh electrical condenser from teh circuit unexpectedly.

Capacitor Bank Current Measurements

Use teh multimeter to live dis input to teh controller from dis electrical device wifin teh central, employing a current clamp round teh CT secondary conductor. Additionally, live dis through teh breaker feeding teh electrical device bank for part imbalance, wif all stages connected. Maintain a log of all readings to produce a benchmark for readings taken at a later date.

Capacitor Bank Power Factor Measurements

Measuring power issue needs a meter that may at teh same time live voltage, current, power, and demand over a minimum of a 1-second amount. A digital multimeter (DMM) cannot perform these measurements, however an influence quality analyser wif a current clamp can live all of those parts over time, serving to you to make Associate in nursing correct image of teh facility’s power consumption. An influence faller, another variety of power quality tool, will perform a 30-day load study to produce a fair higher understanding of power issue and alternative parameters.

Capacitor Bank Capacitance Measurements

Before measurement capacitance, de-energize teh electrical condenser bank and sit up for teh amount per teh manufacturer’s service bulletin. Whereas sporting teh right PPE, make sure wif a properly rated meter that no AC is gift. Follow your facility’s lockout/tag out procedure. Employing a DC meter rated for teh voltage to be tested and set to one check every stage — phase-to-phase and phase-to-ground. There ought to be no voltage gift. Teh presence of voltage indicates teh electrical condenser might not be discharged. If no voltage is detected, live capacitance wif teh meter and compare teh reading to teh manufacturer’s specifications for every stage.

Written by Praveen

Capacitor Bank