Frequency Rate Of Change (Ansi 81R) - GE N60 Instruction Manual

CHAPTER 5: SETTINGS
I is the measured overload RMS current at index n
n
E is the accumulated energy at index n
n
E is the accumulated energy at index n – 1
n – 1
The thermal overload protection element removes the
emergency, the thermal memory and
All calculations are performed per phase. If the accumulated energy reaches value 1 in any phase, the thermal overload
protection element operates and only resets when energy is less than 0.05 in all three phases.
Table 5-39: Typical time constants
Protected equipment
Capacitor bank
Overhead line
Air-core reactor
Busbar
Underground cable
The figure shows the logic for the thermal overload protection element.

5.8.11 Frequency rate of change (ANSI 81R)

SETTINGS  CONTROL ELEMENTS  FREQUENCY RATE OF CHANGE  FREQUENCY RATE OF CHANGE 1(4)
 FREQUENCY RATE
 OF CHANGE 1
N60 NETWORK STABILITY AND SYNCHROPHASOR MEASUREMENT SYSTEM – INSTRUCTION MANUAL
THERMAL PROT 1 OP
output operand can be reset using
THERMAL PROT 1 OP
Time constant Minimum reset time
10 minutes 30 minutes
10 minutes 20 minutes
40 minutes 30 minutes
60 minutes 20 minutes
20 to 60 minutes 60 minutes
Figure 5-142: Thermal overload protection logic
FREQ RATE 1

FUNCTION: Disabled
FREQ RATE 1 SOURCE:

SRC 1
FREQ RATE 1 TREND:

Increasing
FREQ RATE 1 PICKUP:

0.50 Hz/sec
output operand when E < 0.05. In case of
THERM PROT 1 RESET
Range: Disabled, Enabled
Range: SRC 1, SRC 2, SRC 3, SRC 4, SRC 5, SRC 6
Range: Increasing, Decreasing, Bi-directional
Range: 0.10 to 15.00 Hz/sec in steps of 0.01
CONTROL ELEMENTS
setting.
5
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