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Similar to Improving the reliability of feeder protection using digital relays
Similar to Improving the reliability of feeder protection using digital relays (20)
Improving the reliability of feeder protection using digital relays
- 1. By Improving the Reliability of Feeder protection using Digital relays Sudarshan Reddy Electrical Engineer Intern Mill Electric Bagdad
- 2. Protective Relaying is one of several features of the power system design that is concerned with minimizing damage to equipment and interruptions to service when electrical, mechanical, or natural failures occur. Functional characteristics of Protective relaying Types of Protective relays Definition of Protective Relaying Electro-mechanical relay Solid-state relay Digital relay
- 3. 3 Natural causes Why do we need protective relaying
- 4. 4 Who’s Minding the Store? If the Controllers and State Estimators are the Watchdogs of our Electric System and the Breakers are the Muscle – Protective Relaying is the Brain of our System
- 5. 5 Protective relays – Personal safety Arc-Flash Reasons for Arc-Flash Arc Flash- Hazards Methods to reduce Arc-Flash Hazard i. Enable instantaneous settings ii. Arc-Flash detection iii. Fast bus trip scheme
- 6. 6 CT saturation can be minimized One digital relay can replace a bank of analog devices Self monitoring and time stamped event recording Communication using Modbus Custom functions can be programed Improved performance Do we need Digital relays? Solid-state relay Digital relay
- 7. 7 Feeder protection 50 51 50 50 5051 51 51 5150 GE MULTILIN 850 GE MULTILIN 850 GE MULTILIN 850GE MULTILIN 850 GE MULTILIN 850 B1 B2 B3 B4 B5 115Kv 12.47Kv 12.47Kv Reclaim System Conveyor systemPIT loop SX and PIT area
- 8. 8 Factors to be considered in Feeder protection Fault current CT ratio Protective relay characteristics Cable Ampacity Load current Protective device ratings Coordination
- 9. 9 Coordination 0.01 0.1 1 10 100 1000 100 1000 10000 100000 Timeinsec Current(A) Fuse melting curve ANSI very inverse curve ANSI very inverse curve B1 B3 50 51 50 51 utility XFMR 115/12.47Kv CT 2000:5 Fuse Breaker 𝐼𝑓=2,000A B1 B3
- 10. Solid state Relays Cost of each Relay = $2,500 Total cost of relays for each feeder = 2,500*3= $7,500 Wiring cost = $500 Cost of Maintenance = $ 1000 Takes more time to Install Total Cost of protection of each feeder= $9,000 Digital Relays Cost of each Relay = $6,300 Total cost of relays for each feeder = 6,300*1= $6,300 Wiring cost = $400 Cost of Maintenance = $ 800 Takes less time to Install Total Cost of protection of each feeder= $7,500 10 Cost benefits
- 11. 11 Mining Industry – Electricity Reliability Safety is Increased Conclusion
- 12. 12
Editor's Notes
- Functional characteristics Sensitivity- assurance that the protection will perform correctly Selectivity- maximum continuity of service with minimum system disconnection Speed- minimum fault duration and consequent equipment damage
- Bottom line is to be reliable i.e., the down time should be as low as possible. Cause of Down time: Natural causes, human errors, etc…
- For example, while I am cooking, I am careful to avoid the hot burner on the stovetop. But if I don’t pay attention and accidently touch the burner… this is unfortunate, but it’s my fault and immediately my brain will tell me to remove your hand instantly. Similarly, as long as the electrical system maintains the proper distance between the normal current level and the overcurrent point everything is OK. But, if a fault occurs in our system, protective devices will act like my brain and instantly send a trip signal to circuit breaker to isolate the fault.
- Arc flash is a potential Electrical Hazard in Industrial areas. Arc flash is due to insulation break down, corrosion, Accidental touching or dropping of tools. Hazards- fire, heat, and radiation which cause blindness and severe burns to humans. Sparks over a wide area and pressure wave.
- As burden is really low for the digital relays so therefore, less chance of CT saturation Digital relays can do Multi functions i.e., Single relay can operate for Multiple functions By using these relays, we can monitor the breaker status and fault recording We can communicate using Modbus communication
- This is the one-line diagram of a feeder. If there is a fault on the system, nearest protective device is to be operated first with a minimum time delay and increase the time dial for the upstream devices so that if down stream device is failed to operate, upstream device will operate with some time delay.
- Relays need to sense the fault current and gives trip signal to breaker. CTs are used to measure the current. Relays follow their characteristics curves in order to trip the breaker in minimal time for a given fault current. Relay settings are based on load current and cable ampacity, as we need to protect the cable. If the fault current is greater than breaker interrupting capacity, then breaker will explode.
- Systematic application of relays in the electrical power system, which, in response to a fault or overload, will remove only a minimum amount of equipment from service. Coordination study- organized time-current study of all devices in series from the utilization device to the source Study is comparison of time it takes the individual devices to operate for a given fault
- Therefore, Digital relays are more economical than solid state relays.
- In mining industry, electricity is the most important factor for continuous mine operations. All our operations are 24x7, we need electricity all the time i.e., we should be more reliable otherwise we may lose a lot of money. As safety is our main concern, by using these digital relays we can reduce the potential electrical hazards and create a safe work environment. By implementing this project, we can achieve both safety and reliability to our system.