Basler Electric DECS-400 - Manual (Page 49)

9369700990 Rev R 37
Transient Boost
Note
Effective with firmware version 1.09, transient boost voltage settings
are based on the voltage setpoint. In all previous firmware versions,
transient boost voltage settings were based on the rated voltage.
The transient excitation boosting function improves response to successive faults by providing increased
excitation support. When a simultaneous line current increase and line voltage decrease occurs, the
DECS-400 compensates by elevating the voltage setpoint above the nominal setpoint. When the line
voltage recovers, the voltage setpoint is restored to the nominal value.
Fault detection is controlled by a voltage threshold setting, a current threshold setting, and a duration
setting. The fault voltage threshold is expressed as a percentage of the AVR setpoint and has an
adjustment range of 0 to 100%. The fault current threshold is expressed as a percentage of the rated field
current and has an adjustment range of 0 to 400%. The duration setting determines how long a fault
condition is tolerated before the setpoint is adjusted. A setting within the range of 0 to 1,000 milliseconds
is possible.
Setpoint adjustment is controlled by a voltage setpoint boosting level, a clearing voltage threshold, and a
clearing voltage delay. The setpoint boosting level is expressed as a percentage above the AVR setpoint
and has an adjustment range of 0 to 100%. Transient boost is disabled once the line voltage recovers
above the clearing voltage threshold. The clearing voltage threshold is expressed as a percentage below
the AVR setpoint and has an adjustment range of 0 to 50%. The clearing voltage delay determines how
long the line voltage must exceed the clearing voltage threshold before setpoint adjustment is terminated.
A setting within the range of 0 to 1,000 milliseconds is possible.
Protection Functions
Twelve protection functions within the DECS-400 protect against the following conditions.
•
Exciter diode failure
•
Field overcurrent
•
Field overtemperature
•
Field overvoltage
•
Generator frequency less than 10 hertz
•
Generator overvoltage
•
Generator undervoltage
•
Loss of field (40Q)
•
Loss of Field Isolation Transducer
•
Loss of sensing voltage
•
Volts per hertz (24)
An active protection function is annunciated at the front panel display, through the BESTCOMS interface,
and through the RS-485 Modbus interface (Com 2). Any of the DECS-400’s six programmable output
relays can be configured to annunciate an active protection function. DECS-400 protection functions are
described in the following paragraphs.
Field Overcurrent
Field overcurrent is annunciated when the field current level increases above the Field Overcurrent
Pickup Level setting for a definite amount of time. The Dial setting acts as a linear multiplier for the time to
an annunciation. The Pickup Level setting and Dial setting are related by an inverse function. This means
that the higher the field current climbs above the pickup level, the shorter the time to annunciation will be.
The Pickup Level setting is adjustable from 0.1 to 9,999 Adc in 0.01 Adc increments. The Dial setting is
adjustable from 0.1 to 20.0 seconds in 0.1 second increments. Field overcurrent protection can be
enabled and disabled without altering the Pickup Level and Dial settings.
DECS-400 Functional Description