Protection of Industrial Power Systems

by DAVIES

• ISBN13: 9780750626620
• ISBN10: 0750626623
• eBook ISBN(s): 9780080515281, 9780750626620
• Edition: 2nd
• Format: Paperback
• Copyright: 1998-03-06
• Publisher: Elsevier Science
• More Book Details
• Purchase Benefits

Summary

The protection which is installed on an industrial power system is likely to be subjected to more difficult conditions than the protection on any other kind of power system. Starting with the many simple devices which are employed and covering the whole area of industrial power system protection, this book aims to help achieve a thorough understanding of the protection necessary. vital aspects such as the modern cartridge fuse, types of relays, and the role of the current transformer are covered and the widely used inverse definite-minimum time overcurrent relay, the theory of the Merz-Price protection system and the development of the high-impedance relay system are critically examined. This new edition has come about in response to the dramatic change from the use of electro-magnetic relays to electronic and micro-processor relays which figure in practically all new installations. Therefore, although the theory and usage are the same, the application can be much improved owing to the increased range and accuracy and the added facilities provided with the modern relays. This book reflects the change and explains the technical advantages.

Table of Contents

Preface to the second edition	ix	(2)
Preface to the first edition	xi
1 Simple protection devices	1	(18)
Direct-acting trip	2	(1)
Thermal trip	2	(1)
Time-limit fuses	3	(3)
Thermal overload devices	6	(1)
Oil dashpots	6	(1)
Fuses	7	(8)
Moulded-case circuit-breakers	15	(4)
2 Relays	19	(22)
Induction relays	19	(3)
Typical applications	22	(5)
Attracted-armature relays	27	(2)
Typical applications	29	(1)
Moving-coil relays	30	(3)
Thermal relays	33	(1)
Timing relays	34	(1)
Design	34	(3)
Static relays	37	(4)
3 Current and voltage transformers for protection	41	(15)
Current transformers	41	(1)
Construction	41	(1)
Design	42	(1)
Burden	43	(1)
Operation	44	(2)
Open-circuited current transformer	46	(1)
Short-time factor	47	(1)
Accuracy limit factor	47	(1)
Specification of current transformers	48	(1)
Rated secondary current	49	(1)
Secondary winding impedance	49	(1)
Primary windings	50	(1)
Application	50	(1)
Effect of CT magnetising current on relay setting	51	(1)
Residual connection	52	(1)
Quadrature or air-gap current transformers	52	(1)
Summation current transformer	52	(1)
Voltage transformers	52	(1)
Accuracy	53	(1)
Protection	54	(1)
Residual connection	54	(1)
Capacitor voltage transformers	55	(1)
4 Fault calculations	56	(25)
Impedance	56	(1)
Fault level	56	(6)
Generators	62	(4)
Cables	66	(3)
Source impedance	69	(1)
Motors	69	(1)
Practical example	69	(8)
Current distribution	77	(1)
Earth faults	78	(3)
5 Time-graded overcurrent protection	81	(21)
Settings	82	(1)
Time-multiplier setting	83	(3)
Application	86	(4)
Discrimination with fuses	90	(1)
Typical calculation	91	(4)
Earth-fault protection	95	(1)
Directional protection	96	(1)
Directional relays	97	(1)
Very inverse characteristic	98	(1)
Extremely inverse characteristic	99	(1)
High multiples of setting	100	(2)
6 Unit protection	102	(24)
Relays	105	(1)
Application	106	(3)
Protection of a motor	109	(1)
CT knee-point voltage	110	(1)
Overall setting	110	(1)
The residual connection	111	(1)
Busbar protection	112	(5)
Phase and earth-fault schemes	117	(1)
Settings	118	(2)
Current setting	120	(2)
Duplicate-busbar protection	122	(1)
Mesh-connected substation	122	(1)
Biased differential protection	122	(4)
7 Transformer protection	126	(22)
Types of fault	126	(1)
Differential protection	127	(1)
Magnetising inrush	128	(1)
Tap-changing	129	(2)
Biased systems	131	(1)
High-speed biased systems	131	(1)
Earth-fault protection	132	(2)
Protection of an earthed-star winding	134	(2)
Protection of the delta winding	136	(1)
Buchholz protection	136	(2)
Overcurrent protection	138	(1)
Instantaneous high-set overcurrent protection	138	(1)
Overload protection	139	(1)
Protection of a typical industrial installation	139	(2)
Restricted earth-fault protection	141	(2)
Balanced earth-fault protection	143	(1)
Overcurrent protection	143	(3)
Standby earth-fault protection	146	(2)
8 Feeder protection	148	(19)
Differential protection	148	(1)
Factors affecting the design	149	(5)
Practical systems	154	(3)
Teed feeder differential protection	157	(1)
Transformer-feeder protection	158	(2)
Intertripping	160	(1)
Auxiliary equipment	161	(2)
Electronic relays	163	(1)
Impedance protection	163	(4)
9 Motor protection	167	(16)
Abnormal conditions	170	(1)
Overload protection	170	(1)
Phase unbalance	171	(1)
Stalling	172	(1)
Insulation failure	172	(3)
Settings	175	(3)
Static relays	178	(1)
Differential protection	178	(1)
Loss of supply	179	(2)
Synchronous motors	181	(2)
10 Generator protection	183	(14)
Insulation failure	183	(1)
Earthing by resistor	183	(1)
Earthing by transformer	184	(1)
Stator protection	184	(1)
Earth-fault protection	185	(1)
Rotor earth-fault protection	186	(2)
Unsatisfactory operating conditions	188	(1)
Overcurrent protection	189	(2)
Overload	191	(1)
Failure of prime mover	191	(1)
Loss of field	192	(1)
Overspeed	192	(1)
Overvoltage	193	(1)
Protection of generator/transformer units	193	(3)
Unit transformers	196	(1)
Parallel operation (public supply)	196	(1)
11 Control circuits	197	(10)
Batteries	200	(1)
Power factor correction	201	(6)
12 Testing	207	(20)
Works tests	207	(1)
Tests on site	208	(1)
Commissioning tests	208	(4)
CT magnetising characteristic curves	212	(4)
Relay characteristic check	216	(6)
Static relays	222	(1)
Insulation tests	222	(1)
Tripping circuit check	223	(1)
Routine maintenance tests	223	(1)
Test equipment	223	(1)
Care of protection relays	224	(3)
Index	227