GE D90 Plus Instruction Manual page 201

CHAPTER 7: PROTECTION
FlexCurves™
Definite time curve
Recloser curves
Phase time overcurrent
PLUS
D90 LINE DISTANCE PROTECTION SYSTEM – INSTRUCTION MANUAL
The custom FlexCurve™ shapes are defined as follows.
The terms in the above equations are defined as follows.
• T represents the operate time in seconds.
operate
• TDM represents the multiplier setting.
• I represents the input current.
• I represents the pickup current setting value.
pickup
• T represents reset time in seconds, assuming the energy capacity is 100% and the
reset
reset mode is timed.
The definite time curve shape operates as soon as the pickup level is exceeded for a
specified period of time. The base definite time curve delay is in seconds. The curve
multiplier of 0.00 to 600.00 makes this delay adjustable from instantaneous to 600.00
seconds in steps of 10 ms. The definite time curve shapes are defined as follows.
The terms in the above equations are defined as follows.
• T represents the operate time in seconds.
operate
• TDM represents the multiplier setting.
• I represents the input current.
• I represents the pickup current setting value.
pickup
• T represents reset time in seconds, assuming the energy capacity is 100% and the
reset
reset mode is timed.
Plus
The D90 uses the FlexCurve™ feature to facilitate the programming of 41 recloser
curves. Refer to the FlexCurves settings section for additional details on the recloser
curves.
The phase time overcurrent element can provide a desired time delay operating
characteristic versus the applied current or be used as a simple definite time element. The
phase current input quantities may be programmed as fundamental phasor magnitude or
total waveform RMS magnitude as required by the application.
Two methods of resetting operation are available: timed and instantaneous. For example, if
the element reset characteristic is set to instantaneous and the element is blocked, the
time accumulator will be cleared immediately.
The phase time overcurrent pickup can be dynamically reduced by a voltage restraint
feature. This is accomplished via the multipliers corresponding to the phase-to-phase
voltages of the voltage restraint characteristic curve. The pickup level is calculated as
multiplier value times the programmed pickup. If the voltage restraint feature is disabled,
the pickup level always remains at the set value.
GROUPED PROTECTION ELEMENTS
Eq. 16
Eq. 17
Eq. 18
Eq. 19
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