GE 845 User Manual

4–350 845 TRANSFORMER PROTECTION SYSTEM – INSTRUCTION MANUAL
FLEXLOGIC CHAPTER 4: SETPOINTS
HYSTERESIS
Range: 0.1 to 50.0% in steps of 0.1%
Default: 3.0%
This setting defines the pickup – drop out relation of the element by specifying the width
of the hysteresis loop as a percentage of the pickup value as shown above in the
Direction, Pickup, and Hysteresis setpoints figure.
RATE OF CHANGE TIME UNIT (dt)
Range: millisecond, second, minute
Default: milliseconds
This setting specifies the time base dt when programming the FlexElement as a rate of
change element.
The setting is applicable only if the Operating Mode is set to “Delta”.
RATE OF CHANGE TIME
Range: 40 to 65535 in steps of 1
Default: 40
This setting specifies the duration of the time interval for the rate of change mode of
operation.
The setting is applicable only if the Operating Mode is set to “Delta”.
EXAMPLES
13.8 kV power system:
• Phase VT Connection: Wye
• Phase VT Secondary: 66.4 V
• Phase VT Ratio: 120:1 (phase to neutral primary voltage = 120*66.4 = 7968 V)
• Aux VT Connection: Vab
• Aux VT Secondary: 115 V
• Aux VT Ratio: 120:1(phase-phase primary voltage = 13800V)
• Phase CTs Primary: 2000 A
• Ground CT Primary: 500 A
• Frequency: 60Hz
Phase Angle DegBASE = 360 deg
Harmonic Content H
BASE
= 100% of nominal
THD THD
BASE
= 100%
Frequency f
BASE
= nominal frequency as entered under the SYSTEM
SETUP menu
Volt/Hz BASE = 1.00
RTDs BASE = 1.00°C
I
2
t (arcing Amps) BASE = 2000 kA
2
*cycle
Differential and Restraint currents
(Percent Differential)
I
BASE
= CT primary from the CT bank selected for Winding 1
(the same base as the one for 87T element)
Differential and Restraint currents
(RGF)
I
BASE
= CT primary from the CT bank selected for the RGF
element (the same base as the one for RGF element)
Winding Hottest-Spot BASE = 1.00°C
Loss of Transformer Life LOL
BASE
= 180000 hours
Aging Factor AAF
BASE
= 1.00
Harmomic Derating HDF
BASE
= 1.00
Xfmr Overload OL
BASE
= 100%
Measured or calculated analog
value related to:
Base Unit

GE 845 Specifications

General

Brand	GE
Model	845
Category	Protection Device
Language	English