Voltage Dip Compensators
VDC PREVENT PRODUCTION DOWN TIME CAUSED
BY MOMENTARY VOLTAGE SAGS.
reliability of electrical power to industry is
in general very high, nevertheless, voltage sags
or dips do occur. These instabilities are caused
by short circuits, lightning strikes on overhead
power lines and heavy load switching. The
duration of such faults is generally shorter
than one second. Power Quality data shows that
voltage sags with a maximum depth of around 50%
constitute 92% of all events.
Most plant can ride through these voltage
dips by virtue of their mechanical and
electrical inertia. However, this is not the
case with electrically held-in contactors and
relays that control the machinery. Contactors
typically drop out from 5ms to 20ms after the
start of a voltage sag with a depth of 32% -
47%. Each short voltage dip now becomes a power
failure and the plant must be restarted. This
can be complicated, time-consuming and costly.
maintain the switchgear control voltage during
voltage sags, effectively keeping the plant
connected. The stored electrical and magnetic
energy is allowed to flow, supporting the
mechanical inertia of the machinery. When the
power recovers after a short voltage dip, the
plant is still running at near synchronous
speed, the inrush currents will be small and the
stress to the system minimal. The VDC provides
an economic solution for users who need their
equipment to comply with the SEMI F47 standard
for voltage sag immunity.
No batteries; no maintenance.
Able to withstand high inrush currents.
Small footprint, easy to retrofit.
Support exceeds SEMI F47 standard
Handles inductive and low power factor
Losses incurred by these power quality events
far outweigh the cost of installing the VDC and investment payback is
achieved in a short time.