1–16 845 TRANSFORMER PROTECTION SYSTEM – INSTRUCTION MANUAL
SPECIFICATIONS CHAPTER 1: INTRODUCTION
UNDERFREQUENCY (81U)
Pickup Level: .........................................................20.00 to 65.00 Hz in steps of 0.01
Dropout Level:......................................................Pickup + 0.03 Hz
Pickup Time Delay: ............................................0.000 to 6000.000 s in steps of 0.001s
Dropout Time Delay:.........................................0.000 to 6000.000 s in steps of 0.001s
Minimum Operating Voltage:........................0.000 to 1.250 x VT in steps of 0.001 x VT
Minimum Operating Current:........................0.000 to 30.000 x CT in steps of 0.001 x CT
Level Accuracy: ...................................................± 0.001 Hz
Timer Accuracy:..................................................± 3% of delay setting or ± ¼ cycle (whichever is greater)
from pickup to operate
Operate Time: ......................................................typically 7.5 cycles at 0.1 Hz/s change
typically 7 cycles at 0.3 Hz/s change
typically 6.5 cycles at 0.5 Hz/s change
FAST PATH:
Typical times are average Operate Times including variables such as frequency change
instance, test method, etc., and may vary by ± 0.5 cycles.
OVERFREQUENCY (81O)
Pickup Level: .........................................................20.00 to 65.00 Hz in steps of 0.01
Dropout Level:......................................................Pickup - 0.03 Hz
Pickup Time Delay: ............................................0.000 to 6000.000 s in steps of 0.001 s
Dropout Time Delay:.........................................0.000 to 6000.000 s in steps of 0.001 s
Minimum Operating Voltage:........................0.000 to 1.250 x VT in steps of 0.001 x VT
Level Accuracy: ...................................................± 0.001 Hz
Timer Accuracy:..................................................± 3% of delay setting or ± ¼ cycle (whichever is greater)
from pickup to operate
Operate Time: ......................................................typically 7.5 cycles at 0.1 Hz/s change
typically 7 cycles at 0.3 Hz/s change
typically 6.5 cycles at 0.5 Hz/s change
FAST PATH:
Typical times are average Operate Times including variables such as frequency change
instance, test method, etc., and may vary by ± 0.5 cycles.
FREQUENCY RATE OF CHANGE (81R)
df/dt Trend:............................................................Increasing, Decreasing, Bi-directional
df/dt Pickup Level:..............................................0.10 to 15.00 Hz/s in steps of 0.01 Hz/s
df/dt Dropout Level: ..........................................96% of Pickup Level
df/dt Level Accuracy:........................................80 mHz/s or 3.5%, whichever is greater
Minimum Frequency:........................................ 20.00 to 80.00 Hz in steps of 0.01 Hz
Maximum Frequency: ...................................... 20.00 to 80.00 Hz in steps of 0.01 Hz
Minimum Voltage Threshold: ........................0.000 to 1.250 x VT in steps of 0.001 x VT
Minimum Current Threshold: ........................0.000 to 30.000 x CT in steps of 0.001 x CT
Pickup Time Delay: ............................................0.000 to 6000.000 s in steps of 0.001 s
Timer Accuracy:..................................................± 3% of delay setting or ± ¼ cycle (whichever is greater)
from pickup to operate
95% Settling Time for df/dt: ..........................< 24 cycles
Operate Time: ......................................................typically 10 cycles at 2 × Pickup
RTD PROTECTION
Pickup:......................................................................1°C to 250°C in steps of 1°C
Hysteresis: .............................................................2°C
Timer Accuracy:..................................................<2 s
Elements:................................................................Trip and Alarm
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