Capacitor Bank Maintenance

The proportionality rate among the powers is defined as Power factor and measured in kilowatts (kW) whereas apparent power, measured in kilovolt-amperes (kVA), it is the absolute fundamental that concern upon the electric efficiency to distribute voltage and current, externally mark for in case it actually works or not. By adding capacitors to the 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 the most basic application. When the power factor drop below the stated values, Power factor correction capacitors can slow down the energy charge by bypassing the standard electric utilities charge. These capacitors are installed when their inductive loads cause power factor complication to the 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 with a discharge circuit, a shock risk exists for an extended period in case the circuit be ruined. So extreme caution is must when testing is done with the voltage applied. Capacitor bank maintenance requires preliminary to the individual equipment and its application to perform the task. Additional threats are involved in working with current transformer (CT) circuits, along with the wiring and shorting block. Howbeit the capacitor bank been de-energized, there is a possibility of electrical shock from the CT wiring, owing to the location of the CT in the switchboard. It can develop a lethal voltage across its terminals.

Visual Inspection and Cleaning

A entire visual analysis of the 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 the units
5. Re-energizing the capacitors, implement an insulation integrity test from the bus phase-to-phase and phase-to-ground points.

Capacitor Bank Infrared Inspection

The most valuable tool for evaluating electrical condenser banks may be a thermal imager. The system ought to be energized for a minimum of one hour before testing. To begin, check the controller show to work out if all the stages square measure connected. Next, verify that the cooling fans square measure operational properly. Conduct AN infrared examination of the enclosure before gap the doors. Supported your arc flash assessment, wear the desired PPE once playacting tasks close to energized instrumentality. Examine power and management wiring with the thermal imager, yearning for loose connections. A thermal analysis can determine a nasty affiliation by showing a temperature increase because of the extra resistance at the purpose of affiliation. A decent affiliation ought to live no over 20 °F higher temperature than the 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 the number of correction offered. Some unit’s square measure equipped with blown fuse indicators; others don’t seem to be. If you discover a blown fuse, stop working the complete bank, and confirm what caused the 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 the time of examination, then it ought to be cooler. Additionally detain mind that the temperature of parts may well be higher with the higher sections because of convection. However, if in keeping with the controller all stages square measure connected, tan temperature variations typically indicate a tangle. For instance, high could cause the capacitor’s internal pressure device to work before the external fuse, therefore removing the electrical condenser from the circuit unexpectedly.

Capacitor Bank Current Measurements

Use the multimeter to live this input to the controller from this electrical device within the central, employing a current clamp round the CT secondary conductor. Additionally, live dis through the breaker feeding the electrical device bank for part imbalance, with 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 the 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 analyzer with a current clamp can live all of those parts over time, serving to you to make Associate in nursing correct image of the facility’s power consumption. An influence feller, 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 the electrical condenser bank and sit up for the amount per the manufacturer’s service bulletin. Whereas, sporting the right PPE, make sure with a properly rated meter that no AC is gift. Follow your facility’s lockout/tag out procedure. Employing a DC meter rated for the 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. The presence of voltage indicates the electrical condenser might not be discharged. If no voltage is detected, live capacitance with the meter and compare the reading to the manufacturer’s specifications for every stage.