Suggestion on How to Use Industry Trainers are

Suggestion on How to Use • Industry Trainers are encouraged to use this material in their sessions • Download the presentation file • Print the Notes pages and read them as you view the presentation in the “Slide Show” view. In this way you see the slides in large format and have animation (when available) © 2015 Eaton. All Rights Reserved. . 1

Ground Fault Protection © 2015 Eaton. All Rights Reserved. .

Ground Fault Protection • All ground faults = short circuits • But all short circuits are NOT = ground faults • Bolted ground faults (cb or fuse) • Low level ground faults = shock/burndown • Need for additional protection • Therefore ground fault protection © 2015 Eaton. All Rights Reserved. . 3

Ground Fault Protection • Ground Fault protection is essential for safety of personnel and equipment • The degree of protection depends upon the device selected. • Ground Fault Protection Devices • Ground Fault Circuit Interrupter (GFCI) – People Protection • Ground Fault Protection of Equipment (GFP) – Equipment Protection © 2015 Eaton. All Rights Reserved. . 4

GFCI Protection • NEC Article 100 – GFCI Definition • A device intended for the protection of personnel that functions to de-energize a circuit or portion thereof within an established period of time when a current to ground exceeds the values established for a Class A device. • Note: Class A ground-fault circuit interrupters trip when the current to ground has a value in the range of 4 m. A to 6 m. A. © 2015 Eaton. All Rights Reserved. . 5

GFCI Protection • Provides protection against electrical shock and electrocution hazards. • Incorporates a current sensing device that monitors the current difference between the ungrounded (hot) and neutral (grounded) conductor. © 2015 Eaton. All Rights Reserved. . 6

GFCI Protection • GFCI Construction and Operation • If the current difference between the hot and neutral conductor exceeds 4 -6 m. A, the GFCI will trip. ST SS Circ Push-to-Test 20 A GFCI L N Sensor © 2015 Eaton. All Rights Reserved. . 120 V Load 7

GFCI Protection • Man completes circuit between the line conductor and ground…current does not return through neutral back to source…Sensor picks up leakage current and GFCI trips. . Man Saved. ST SS Circ Push-to-Test 20 A GFCI L N Sensor R = 1000 OHMS I = V/R I = 120/1000 = 0. 12 A © 2015 Eaton. All Rights Reserved. . 8

GFCI Protection • Man completes circuit between the line conductor and neutral…current in equals current out…Sensor does not pick up leakage current…GFCI does not trip…. Man NOT happy!!! ST SS Circ 20 A GFCI L N Sensor R = 1000 OHMS I = V/R = 120/1000 = 0. 12 A © 2015 Eaton. All Rights Reserved. . 9

GFCI Protection • NEC 210. 8(A) Dwelling Units • Requires ground-fault circuit-interrupter protection for personnel on all 125 V, single-phase, 15 - and 20 -ampere receptacles installed in specified locations • Specified locations include bathrooms, garages, outdoors, crawl spaces, unfinished basements, kitchens, wet bar sinks, boathouses, and laundry areas. © 2015 Eaton. All Rights Reserved. . 20 A CB Bathroom Receptacle GFCI protection must be provided per NEC 210. 8(A), either by CB or bathroom receptacle 10

GFP Protection • NEC Article 100 – Ground-Fault Protection of Equipment Definition • A system intended to provide protection of equipment from damaging line-to-ground fault currents by operating to cause a disconnecting means to open all ungrounded conductors of the faulted circuit. This protection is provided at current levels less than those required to protect conductors from damage through the operation of a supply circuit overcurrent device. © 2015 Eaton. All Rights Reserved. . 11

GFP Protection – Why? • Rat causes phase to ground fault • I = V/R 277 V 3, 000 A CB C A I = 277/0. 1 480 V 27 7 V I = 2, 770 A • B 480 V 3000 A CB will not trip! R = 0. 1 OHMS N © 2015 Eaton. All Rights Reserved. . 12

Ground Fault Protection 230. 95 • Requires ground-fault protection for each solidly grounded wye service disconnect where: • System voltage is more than 150 V to ground, but not exceeding 600 V phase to phase • Rated 1000 A or more • Maximum ground-fault current setting – 1200 A • Maximum ground-fault time-delay setting – 1 second for ground fault currents equal to or greater than 3, 000 A. © 2015 Eaton. All Rights Reserved. . 13

Ground Fault Protection 230. 95 • Ground Fault Protection is not required: • For fire pumps (not permitted) or continuous process industrials where a non-orderly shutdown would result in additional hazards. • 240 V/120 single phase or 240 V three phase systems. • Services (or feeders) above 600 V. • Service with six disconnects or less where each disconnect is less than 1000 amperes. A 4000 ampere service split into 5800 ampere switches would not require GFP. • Delta, ungrounded, or resistance/impedance grounded systems. © 2015 Eaton. All Rights Reserved. . 14

Ground Fault Protection 215. 10 • Ground Fault Protection is required on feeder disconnect switches, in accordance with 230. 95, where: • System voltage is more than 150 V to ground, but not exceeding 600 V phase to phase • Rated 1000 A or more • Exceptions: • Fire pumps or continuous process industrials where a nonorderly shutdown would result in additional hazards. • If ground-fault protection is provided on the supply side of feeder. © 2015 Eaton. All Rights Reserved. . 15

Ground Fault Protection 215. 10 • Ground fault protection as required by 210. 15 © 2015 Eaton. All Rights Reserved. . 16

Ground Fault Protection 215. 10 • GFP not required on feeder equipment when it is provided on the supply side of the feeder (except as required for Health Care Facilities per Article 517) © 2015 Eaton. All Rights Reserved. . 17

Ground Fault Protection 240. 13 • Equipment ground fault protection, in accordance with 230. 95, is required for each disconnect rated 1000 A or more, for 480/277 V systems, that will serve as a main disconnect for a separate building or structure. © 2015 Eaton. All Rights Reserved. . 18

GFP Protection • GFP Can • Sense low magnitude ground faults • Protect equipment against low magnitude ground fault • GFP CANNOT • Protect people or prevent ground faults and electric shock • Protect against 3 phase, phase-phase or phase-neutral faults • Protect against high level ground faults • Guarantee selective coordination – may adversely affect selective coordination © 2015 Eaton. All Rights Reserved. . 19

Ground Fault Protection • Types of GFPs • GFEP (Earth Leakage) • Zero Sequence • Residual (Neutral Ground Strap) © 2015 Eaton. All Rights Reserved. . 20

Earth Leakage (GFEP) • Earth Leakage (GFEP – Ground Fault Equipment Protector) circuit breakers detect ground faults of 30 m. A or more. • Typically Rated 277 V, 100 A or less ST SS Circ Push-to-Test 20 A GFEP L N Sensor © 2015 Eaton. All Rights Reserved. . 277 V Load 21

• CT encloses phase and neutral conductors • 1 CT as shown or 4 CTs (one for each phase and neutral) • CTs Sense current difference • Signals GF Relay • ST Opens Disconnect • Typically available on CB & Fused Switches rated 400 A or more. Zero Sequence GFP 277 V ST C 27 3000 A BPS A 480 V 27 7 V GF Relay 7 V B 480 V N © 2015 Eaton. All Rights Reserved. . 22

Zero Sequence GFP - Operation 277 V ST C 480 V 27 7 V Current does not return through neutral/CT • If current to ground exceeds setting on GF Relay, BPS will shunt trip. GF Relay 3000 A BPS A • B 480 V N © 2015 Eaton. All Rights Reserved. . 23

Residual GFP 277 V ST C 3000 A BPS A 480 V 27 7 V 27 GF Relay 7 V B 480 V N Grounding Strap © 2015 Eaton. All Rights Reserved. . 24

Residual GFP - Operation 277 V ST C 27 3000 A S/F A 27 7 V GF Relay 480 V 7 V B 480 V • Current does not return through neutral • Residual CT senses current • If current through grounding strap exceeds setting on GF Relay, BPS will shunt trip. N © 2015 Eaton. All Rights Reserved. . 25

Calculating Ground Fault Energy • k. W-Cycles can be used to determine amount of damage based upon ground fault energy. • k. W-Cycles = (I X E X t)/1000 • I = Ground fault current • E = 100 V of 277/480 V system • t = Arcing time in cycles © 2015 Eaton. All Rights Reserved. . 26

GFP Protection: k. W-Cycles • Equipment Damage from ground-faults can be measured by k. W-Cycles • 100 k. W-Cycles – Spit marks on Equipment • 2000 k. W-Cycles – Limited damage. Equipment can be put back in operation after cleaning smoked and spotted areas and repairing insulation if necessary • 10, 000 k. W-Cycles – Serious damage. Usually will not burn through. Equipment will probably need parts replaced, such as bus bars. © 2015 Eaton. All Rights Reserved. . 27

GFP Protection: k. W-Cycles • 20, 000 k. W-Cycles – Serious damage. Fault will probably burn through and spread to other sections of equipment. Equipment will need extensive repairs and/or replacement. • Over 20, 000 k. W-Cycles – Much destruction of equipment…fire. Equipment will need extensive repairs and/or replacement. © 2015 Eaton. All Rights Reserved. . 28

k. W-Cycles vs. Fault Current • Protective device selected can determine degree of protection as shown in chart. © 2015 Eaton. All Rights Reserved. . 29

GFP Considerations – Current Limitation This system offers: 1. Some degree of arcing and low magnitude ground fault protection by the ground fault relay operating the switch. 2. Current-limitation for high magnitude ground faults and short-circuits by current-limiting fuses, which provides component protection for the switchgear. This system offers: 1. Some degree of arcing and low magnitude ground fault protection by the ground fault relay operating the circuit breaker. Note: This system does not provide currentlimitation for high magnitude ground faults and short-circuits. © 2015 Eaton. All Rights Reserved. . 30

GFP Considerations - Coordination • A ground fault on a feeder or branch circuit can cause the main device to open. © 2015 Eaton. All Rights Reserved. . 31

GFP Considerations Coordination • The system on the left has a lack of selective coordination – the shortcircuit on the branch device causes the main to open and results in a black-out situation. • The system on the right has selective coordination - only the device nearest the short circuit opens. © 2015 Eaton. All Rights Reserved. . 32

GFP Relay & OCPD Curves • Effective time current curve for line to ground fault with 1600 ampere fuse and ground fault protection set at 1200 amperes (switch clearing time of 4 cycles). © 2015 Eaton. All Rights Reserved. . 33

GFP Relay & OCPD Curves • Effective time current curve for line to ground fault with 1600 ampere circuit breaker and ground fault sensor setting at 1200 amperes. © 2015 Eaton. All Rights Reserved. . 34

GFP Considerations - Coordination • Low Magnitude Ground Fault • Longer ground fault relay delay permits larger feeder fuse to coordinate with main relay. • High Magnitude Ground Fault • Fuses are selectively coordinated. © 2015 Eaton. All Rights Reserved. . 35

GFP Considerations - Coordination • Low Magnitude Ground Fault • A lack of coordination exists for ground faults between 1200 amperes and 1800 amperes. • High Magnitude Ground Fault • Faults greater than 11, 000 A will cause the 200 A and 1200 A Power CB to open. • Adding STD to the 1200 amp Power CB would allow the two CBs to selectively coordinate. © 2015 Eaton. All Rights Reserved. . 36

Ground Fault Protection 517. 17 • If the service or feeder is equipped with ground fault protection in accordance with 230. 95 or 215. 10, the next level of feeders is also required to have ground fault protection. • Separation between the service and feeder ground fault relays must achieve total selective coordination. © 2015 Eaton. All Rights Reserved. . 37

Ground Fault Protection 517. 17 • Service Disconnect is equipped with ground fault protection per 230. 95 • Feeders are equipped with ground fault protection and have manufacturer recommended separation between the two ground fault curves. • Complies with NEC 517. 17 © 2015 Eaton. All Rights Reserved. . 38

Ground Fault Protection 517. 17 • Main - 1200 A Fuse • Feeder - 200 A Fuse • GFP on Main & Feeder • Meets 517 -17 © 2015 Eaton. All Rights Reserved. . 39

© 2015 Eaton. All Rights Reserved. . 40