Method for determining compensation (Power Factor correction Guidelines)

Different types of compensation should be adopted depending on the performance requirements and complexity of control:

1. Fixed, by connection of a fixed-value capacitor bank
2. Automatic, by connection of a different number of steps, allowing adjustment of the reactive energy to the required value
3. Dynamic, for compensation of highly fluctuating loads.

Fixed compensation

This arrangement uses one or more capacitor(s) to provide a constant level of compensation. Control may be:

1. Manual: by circuit-breaker or load-break switch
2. Semi-automatic: by contactor
3. Direct connection to an appliance and switched with it.

These capacitors are installed:

1. At the terminals of inductive loads (mainly motors)
2. At busbars supplying numerous small motors and inductive appliances for which individual compensation would be too costly
3. In cases where the load factor is reasonably constant.

Automatic compensation

This kind of compensation provides automatic control and adapts the quantity of reactive power to the variations of the installation in order to maintain the targeted cos φ. The equipment is installed at points in an installation where the active-power and/or reactive-power variations are relatively large, for example:

1. on the busbars of a main distribution switchboard
2. on the terminals of a heavily-loaded feeder cable.

Where the kvar rating of the capacitors is less than or equal to 15% of the power supply transformer rating, a fixed value of compensation is appropriate. Above the 15% level, it is advisable to install an automatically-controlled capacitor bank.

Control is usually provided by Power Factor Controller which monitors the actual power factor and orders the connection or disconnection of capacitors in order to obtain the targeted power factor. The reactive energy is thus controlled by steps. In addition, the Power Factor Controller provides information on the network characteristics (voltage amplitude and distortion, power factor, actual active and reactive power) and equipment status. Alarm signals are transmitted in case of malfunction.

Connection is usually provided by contactors. For compensation of highly fluctuating loads, the use of active filters or Var compensators  is recommended. Contact ZDDQ Electric for electronic compensation solutions.

ZDDQ Automatic Compensators

L.V automatic capacitor banks

M.V automatic Capacitor banks

Dynamic compensation

This kind of compensation is required when fluctuating loads are present, and voltage fluctuations have to be prevented. The principle of dynamic compensation is to associate a fixed capacitor bank and an electronic var compensator,providing either leading or lagging reactive currents.

The result is continuously varying fast compensation, perfectly suitable for loads such as lifts, crushers, spot welding, etc.

ZDDQ Dynamic Compensators

L.V Active Harmonic Filters

L.V Static Var Generators

M.V STATCOM