6 Protection Functions
P50 Agile P153
6-6
P153/EN M/B
Another possible situation where the timer hold facility may be used to reduce fault clearance times is
for intermittent faults. An example of this may occur in a plastic insulated cable. In this application it is
possible for the fault energy to melt and reseal the cable insulation, thereby extinguishing the fault.
This process repeats to give a succession of fault current pulses, each of increasing duration with
reducing intervals between the pulses, until the fault becomes permanent.
When the reset time is instantaneous, the device will repeatedly reset and not be able to trip until the
fault becomes permanent. By using the Timer Hold facility the device will integrate the fault current
pulses, thereby reducing fault clearance time.
The timer hold facility is available to all three stages of OC and EF functions.
The Definite Time Reset characteristic is applicable for IEC curves / DT.
The value of the Reset Timer depends on the type of the timer associated to the pick-up phase (Earth)
threshold.
Type of timer associated with phase (earth)
threshold
Reset Timer
DT Reset Characteristic
IDMT Reset Characteristic
- For DT time delay
0 – 100s
Not available
- For IDMT IEC time delay
0 – 100s
Not available
- For IDMT IEEE or CO time delay
0 – 100s
Based on RTMS value
(0.025-1.2)
The mathematical formula applicable to the five curves is:
t = RTMS x K
--------------------
1- (I / Is)
α
Where:
t =
Reset time
K =
Factor (see table)
I =
Value of the measured current
Is =
Value of the programmed threshold (pick-up value)
α
=
Factor (see table)
RTMS
Reset time multiplier (RTMS) setting is between 0.025 and 1.2
Description
Standard
K
α
Moderate Inverse
IEEE
4.85
2
Very Inverse
IEEE
21.6
2
Extremely Inverse
IEEE
29.1
2
US Inverse
CO8
5.95
2
US Short Time Inverse
CO2
2.261
2
2.2
Phase Overcurrent Protection
Phase current faults are faults where fault current flows between two or more phases of a three-phase
power system. The fault current may be between the phase conductors only or, between two or more
phase conductors and earth. There are three types of phase fault:
•
Line to Line (accounting for approximately 8% of all faults)
Summary of Contents for Agile P50 Series
Page 3: ...P50 Agile P153 1 Introduction P153 EN M B 1 1 INTRODUCTION CHAPTER 1...
Page 4: ...1 Introduction P50 Agile P153 1 2 P153 EN M B...
Page 10: ...1 Introduction P50 Agile P153 1 8 P153 EN M B...
Page 11: ...P50 Agile P153 2 Safety Information P153 EN M A 2 1 SAFETY INFORMATION CHAPTER 2...
Page 22: ...Chapter 2 Safety Information P50 Agile P153 2 12 P153 EN M A...
Page 23: ...P50 Agile P153 3 Hardware Design P153 EN M B 3 1 HARDWARE DESIGN CHAPTER 3...
Page 24: ...3 Hardware Design P50 Agile P153 3 2 P153 EN M B...
Page 32: ...3 Hardware Design P50 Agile P153 3 10 P153 EN M B...
Page 33: ...P50 Agile P153 4 Front Panel P153 EN M B 4 1 FRONT PANEL CHAPTER 4...
Page 34: ...4 Front Panel P50 Agile P153 4 2 P153 EN M B...
Page 39: ...P50 Agile P153 5 Configuration P153 EN M B 5 1 CONFIGURATION CHAPTER 5...
Page 40: ...P50 Agile P153 5 Configuration P153 EN M B 5 2...
Page 150: ...P50 Agile P153 5 Configuration P153 EN M B 5 112...
Page 151: ...P50 Agile P153 6 Protection Functions P153 EN M B 6 1 PROTECTION FUNCTIONS CHAPTER 6...
Page 152: ...6 Protection Functions P50 Agile P153 6 2 P153 EN M B...
Page 168: ...7 Protection Parameter Settings P50 Agile P153 7 2 P153 EN M B...
Page 189: ...P50 Agile P153 8 Monitoring Control P153 EN M B 8 1 MONITORING CONTROL CHAPTER 8...
Page 190: ...8 Monitoring Control P50 Agile P153 8 2 P153 EN M B...
Page 207: ...P50 Agile P153 9 SCADA Communications P153 EN M B 9 1 SCADA COMMUNICATIONS CHAPTER 9...
Page 208: ...12 SCADA Communications P50 Agile P153 9 2 P153 EN M B...
Page 220: ...12 SCADA Communications P50 Agile P153 9 14 P153 EN M B...
Page 221: ...P50 Agile P153 10 Installation P153 EN M B 10 1 INSTALLATION CHAPTER 10...
Page 222: ...10 Installation P50 Agile P153 10 2 P153 EN M B...
Page 234: ...13 Commissioning Instructions P50 Agile P153 13 2 P153 EN M B...
Page 242: ...12 Maintenance and Troubleshooting P50 Agile P153 12 2 P153 EN M B...
Page 250: ...12 Maintenance and Troubleshooting P50 Agile P153 12 10 P153 EN M B...
Page 252: ...13 Technical Specifications P50 Agile P153 13 2 P153 EN M B...
Page 263: ...P50 Agile P153 14 Wiring Diagrams P153 EN M B 14 1 WIRING DIAGRAMS CHAPTER 14...
Page 264: ...14 Wiring Diagrams P50 Agile P153 14 2 P153 EN M B...
Page 267: ......