15.1 The power factor at each of the CUSTOMER’s Points of Supply shall under all

load conditions not be leading, unless otherwise agreed to by ESKOM.

15.2 The power factor of the load at each of the CUSTOMER’s Points of Supply

shall not be less than 0,9 (naught comma nine) lagging. Should the power

factor be less than 0,9 (naught comma nine) the CUSTOMER shall be required

to install at its own expense suitable apparatus to ensure that this requirement

is complied with.

Real Power or Working Power (kW) - Measured

Reactive Power (kVAr) - Measured

Apparent Power (kVA) - Calculated

Leading Power factor = Dangerous and not easy to manage

Manageable not serious issues

Power Factor = True Power / Apparent Power

Power Factor = Resistance / Impedance

Power Factor = Voltage / Current

Power Factor = Power / 1.73 * Volts * Amps

Never Control to Unity = 1 ( .98 best )

If the Power Factor is 1 you are very close to resonance

Leading Reactive Power:

Produced by Synchronous Capacitors and Capacitor Banks.Consumed by the Capacitive nature of Loads.Leading Reactive power loads are Electric Motors with Capacitor for starting and running, Long TransmissionLines.

The main harmful effect of the leading power factor is, it creates a high voltage in the circuit which can affect theload as well as the power supply circuit.

Charging and discharging capacitors (scienceandmathsrevision.co.uk)

Capacitor Discharging- Explained (learningaboutelectronics.com)

To calculate the time constant of a capacitor, the formula is τ=RC.

This value yields the time (in seconds) that it takes a capacitor to

discharge to 63% of the voltage that is charging it up. After 5 time

constants, the capacitor will discharge to almost 0% of all its

voltage.

Point where you can switch Caps in again at 5T (5 Time Constants) for Industrial caps this time is +_ 7 min.

If this is not done then the voltage will super impose it self. 6.6 -> 12 -> 24-> 48 -> 96 kV. Expect some serious damage to equipment.

Increases heating losses in transformer and distribution equipment.Reduce plant life.Unstable voltage levels.Increase power losses.Upgrades needs == costly equipment.Decreases energy efficiency.Increases electricity cost by paying power factor surcharges.

Causes and Disadvantages of Low Power Factor | Electrical-Technology | All about Electrical Engineering

Why should plant engineers be worried about the power factor? What’s the catch? | EEP (electrical-engineering-portal.com)

Increase in efficiency of system and devices

Low Voltage Drop and cable capacity increases.

Reduction in size of a conductor and cable which reduces cost of the Cooper

An Increase in available power on cables and equipment

Line Losses (Copper Losses) I2R is reduced

Appropriate Size of Electrical Machines (Transformer, Generators etc.)

Saving in the power bill

Back-to-Basics: On Power Factor And Why We Correct It | Power Electronics

Advantages

Reduces the tariff penalties for excessive consumption of Reactive Power

Reduces the apparent power kVA demand, on which standing charges are

usually based

Relieves the supply transformer, which is then able to accept more load if

necessary

Reactive current still flows in all conductors of cables leaving (i.e.

downstream of) the main LV distribution board

For the above reason, the sizing of these cables, and power losses in them, are not improved by the global mode of compensation.

Down side

5 Types of Power Factor Correction | Capacitor bank locations - TheElectricalGuy

Advantages

Reduces the tariff penalties for excessive consumption of kVArs

Reduces the apparent power kVA demand, on which standing charges are usually

based

Relieves the supply transformer, which is then able to accept more load if necessary

The size of the cables supplying the local distribution boards may be reduced, or will

have additional capacity for possible load increases

Losses in the same cables will be reduced

Down side

Reactive current still flows in all cables downstream of the local distribution boards

For the above reason, the sizing of these cables, and the power losses in them, are not improved by

compensation by sector

Where large changes in loads occur, there is always a risk of overcompensation and consequent

overvoltage problems

Advantages

Reduces the tariff penalties for excessive consumption of kVArs

Reduces the apparent power kVA demand

Improve the Power Factor of the piece of Equipment.

Reduces the size of all cables as well as the cable losses (in design)

Significant reactive currents no longer exist in the installation

HUGE ADVANTAGE

Never install PFC equipment where the concrete is reinforced with steel

The steel will be a path for induced circulating current.

Rather reinforce the concrete with Fibre or Kevlar

Good is not always Good or the Best

The voltage across the inductor is equal to the voltage across the capacitor.

The voltage across the resistor is equal to the applied voltage.

The impedance (Z)of the circuit has its lowest value and is equal to (R). Z=R

Circuit current assumes its maximum value because the impedance is minimum.

The power factor for the circuit becomes equal to 1, and the phase angle is zero.

Apparent power has its lowest value and becomes equal to the active power because the powerfactor is 1.

Resonance occurs because the collapsing magnetic field of the inductor generates an electric current in its windings that charges the capacitor,the discharging capacitor provides an electric current that builds the magnetic field in the inductor, and the

process is repeated

A serious concern arising from the use of capacitors in an electrical power system is the possibility of system resonance.

This effect imposes voltages and currents that are substantially higher than would be the case without resonance.

Effect on the circuit is the same as though neither inductance nor capacitance is present. So NO Impedance only Resistance

Harmonic resonance in a power system may be classified as parallel or series resonance, and both types are present in a harmonic-rich environment.

Parallel resonance causes current multiplication, whereas Series resonance produces Voltage magnification.

Substantial damage to capacitor banks would occur when resonance is present

A high probability that other electrical devices / Equipment in the system would also be damaged.

Difference Between Series Resonance and Parallel Resonance i

What are Series RLC Circuit and Parallel RLC Circuit? (apogeeweb.net)

Overloads on distribution systems due to the increase in the RMS current,

overloads on neutral conductors due to the summing of third-order

harmonics

Overloads, vibrations and premature ageing of generators, transformers,

motors, etc., transformer hum,

Overloading and premature ageing of capacitors in power factor correction

equipment,

Distortion of the supply voltage, capable of disturbing sensitive loads,

Disturbances on communications networks and telephone lines.

The Presence of Harmonics can result in increased equipment and

conductor heating, misfiring in variable speed drives, and torque

pulsations in motors and generators.

Harmonics and It’s Effects | Electrical Notes & Articles (wordpress.com)

Power Factor - Explanation, Low Power Factor Correction, Causes of Low PF (byjus.com)

Harmonics that causes serious problems

3rd = Motor = Zero Sequence = Current in Neutral / Star Point5th = Motor = Negative Sequence = Negative Torque / Overheating, Motors, Cables7th = Motor = Positive Sequence = Over exited Positive Torque

Harmonic Current and Voltage Distortion | EC&M (ecmweb.com)

Harmonic distortion: causes and mitigation (capacitorfaks.com)

Harmonics measured at a shaft causing Resonance

EFFECTS OF HARMONICS ON CAPACITORS | Power Quality In Electrical Systems (powerqualityworld.com)

Switching of a capacitor bank in the presence of already energized banks on the same bus.

The transients mainly consist of interchange of current between the banks.

These transient currents can be extremely high in amplitude and frequency and may exceed

the capability of the circuit breaker. Causing a serious failure

Where the capacitor bank is already energized and operating in the steady state and a fault

occurs on the bus, the capacitor bank would discharge into the fault.

It`s magnitude and frequency depend on inductance between the capacitor bank and the fault

location.

Outrush transient can be very severe causing stress in the circuit breaker causing failure and an

explosion.

The voltage magnification is due to the interaction between a distribution-level capacitor bank and

another nearby bank on the transmission system.

Voltage magnification transients can be experienced at the distribution level capacitor.

This could lead to severe over voltages, which could ultimately lead to the failure of the capacitor

bank or Equipment

Arc, Restriking and Recovery Voltages | chakarvyuh (wordpress.com)

Restriking Voltage Transient in a Circuit Breaker - Explanation & Calculation of Restriking Voltage - Circuit Globe

As soon as the contacts separate out an arc is formed. The voltage across the contacts during the arcing period is known as the arc voltage and is relatively low with heavy current arcs of short length.

At current zero it rises rapidly to the peak value since a short circuit current is almost 90° lagging.The translate voltage appearing across the contacts at current zero during arc period is called the restriking voltage. This voltage will probably restrike the arc so that it persists for another half cycle.

SF6 Rotating Arc

Modern Vacuum Bottle

ION 8240 Custom Control ModuleION 7550

Custom Stage Control Module

Doing Power Factor Correction is in evadable == doing it correctly is a choice

Do your home work before you jump into the exercise.

Most important step is Start of by doing an study of your electrical system

Decide what benefit you want out of the exercise

Check your equipment if it is suited for the added capacitance

Make sure that the interlocking is done properly and that the control is relevant

No sophisticated control equipment is necessary, do it with your power quality equipment

installed.