Often, reactive power is not taken into account when designing and constructing an installation. As a result, protection measures may prove inadequate. Reactive power causes additional (reactive) current to flow through the installation, which means the fuse of the protection device may trip. As a direct consequence of tripping (engaging protection) parts of the installation are switched off. This causes significant continuity problems and may also result in a loss of production assets and materials.
Tripping as a result of reactive power
An installation is secured by means of protection devices such as a fuse-link and/or circuit breaker. The fuse may trip during normal operation, causing the power to be cut off. A possible cause of tripping can be overcurrent (when the current is higher than the nominal current).
Reactive currents can cause the fuse to trip in case of overcurrent. Protection is based on the nominal current in the installation. This often also takes a small amount of overcapacity into account. However, in spite of this overcapacity, it is possible that more current will pass through than initially expected. This level of current was not taken into account when specifying protection. A possible cause of this excessive current is reactive power. As the reactive power must be transported through the cabling, it may also cause an increase in current.
Cause of tripping is not always immediately clear
The issue with tripping caused by reactive power is the fact that the cause is not immediately clear. This reactive power will not be visible on the installation’s kilowatt meter, but a considerably higher current will still be visible on the flow meters.
An addition to tripping, reactive power may have consequences such as heat loss, capacity loss, overheating and in certain cases may even lead to fines from the energy supplier.