SATEC C192PF8-RPR - Manual (Page 57)

Chapter 5 PFC Setup and Operation 52
5.3 Capacitor Banks Protection
5.3.1 PFC Protective Actions
The reason for the PFC protection mechanism is to protect the capacitor banks
and contactors against harmful conditions that would lead to extremely high over-
voltage, or would cause undesirable effects such as high transient voltages and
currents and high harmonics. The effect of the PFC protection is automatic
disconnection of the capacitor banks that should occur immediately in the event
of danger to capacitors, or progressively, in less dangerous situations, until alarm
conditions disappear (with minimal cycling whenever possible).
In the C192PF8-RPR, all protective functions are provided through the universal
mechanism of programmable alarm setpoints (see Section 4.6, Alarm/Event
Setpoints Menu).
The PFC itself has no embedded protection functions that may automatically disconnect
the capacitor banks in such situations. With no setpoint protection, the capacitor banks will
remain unprotected against damaging conditions unless external protection is used.
Any number of the 16 programmable setpoints can be used for PFC protection.
Section 5.3.2 provides instructions on how to program certain highly
recommended setpoints for typical alarm conditions. Notice that the effect of the
setpoints does not depend on their order in the setpoint list.
Protection of the capacitors against short circuits should be carried out separately using
either fuses or switches with over-current protection.
The three following setpoint actions are specially intended for the use with the
PFC alarm protection setpoints.
Hard Switch-Off
When alarm override condition is detected, the Hard Switch-Off action
immediately switches out all the capacitor banks including those defined as
permanently switched in. When used with the No-Volt trigger condition (see Table
4-7), this action provides the fastest possible response to voltage interruptions.
Soft Switch-Off
The Soft Switch-Off action switches off the capacitor banks progressively in pre-
set disconnection intervals, while the alarm condition is present. This allows
circumventing over-voltage or high harmonics conditions with minimum cycling of
the capacitor banks. The banks that are defined as permanently switched in are
not affected. After the alarm condition, the PFC will return to automatic operation
after the safety delay which is 50 times the power factor setpoint operate delay.
Stop (Freeze) PFC
This action freezes automatic operation of the PFC until the alarm condition
disappears. No switching operations on the capacitor banks will be performed.
This action does not affect operations in manual mode.