ABB UNITROL 1020 - Extended Operation Lifetime with External Capacitor

Chapter 4 - Installation and Storage 
82 3BHS335648 E82 UNITROL 1020 User Manual
Following instructions must be followed in order not to damage UNITROL
1020
Shunt supply
Excitation power is taken from the generator output over
a shunt transformer
 Always use excitation supply transformer
 Excitation transformer must not exceed 10 kVA
PMG supply
Excitation power is taken form PMG
 PMG output power must not exceed 10 kVA
Auxiliary
Windings
Excitation power is taken from additional stator winding
of the generator
 No measures must be taken
Auxiliary supply
Excitation power is taken directly from an auxiliary power
source
 Use always excitation supply transformer
 Excitation transformer must not exceed 10 kVA
DC battery
Excitation is taken from a battery
 Inrush current must be limited by a resistor
Inrush can be easily calculated assuming that the capacitor voltage is 0V
at startup. The external resistor for 200Vac input is typically 1.5Ω.
NOTICE!
This inrush current must be limited to 200 A average for 10 ms,
otherwise the unit might be damaged
4.5.3 Extended operation lifetime with external capacitor
Operation lifetime is limited by the internal capacitor used to filter the
excitation input power. The operation lifetime is influenced by:
a) Ambient temperature, +10 °C decreases lifetime by factor 2
b) Nominal excitation output current
c) Source of input voltage, DC, 3-phase or single-phase
The following table defines when an external capacitor is needed in order
to have a suitable operation lifetime.