what is the difference between earthed system and unearthed
system.. where do we use unearthed system because in
electrical catalogues always cable for earthed and unearthed
system is given..pls elaborate
- 3 Answers
- 35700 Views
- I also Faced
- E-Mail Answers
Answer Posted / s bhattacharya
BASICALLY AS PER LATEST IEC ALL VOLTAGE SYSTEMS WHETHER
400KV OR 415VOLT THE NEUTRAL HAS TO BE GROUNDED AT EACH
LEVEL IN ONE POINT WHETHER SOLID GROUND OR HIGH IMPEDANCE
GROUND.
THE METHOD OF NEUTRAL GROUNDING DEPENDS ON SYSTEM VOLTAGES
1.FOR HV SYSTEMS GREATER THAN 33KV THE NEUTRAL IS GROUNDED
DIRECTLY TO EARTH.
2.FOR VOLTAGES 33KV TO 4kv THE NEUTRAL IS GROUNDED EITHER
THROUGH NGR OR NGT (AS PER THE SYSTEM REQUIREMENT TO LIMIT
THE SYSTEM SHORT CIRCUIT CURRENT IE LIMIT FAULT LEVEL)AND
THIS IS CALLED UNEARTHED SYSTEM.
3.VOLTAGES 415VOLT SYSTEM GENERALLY NEUTRAL IS DIRECTLY
GROUNDED AND THIS IS CALLED EARTHED SYSTEM.
HIGH IMPEDANCE GROUNDING IE FROM 4kv TO 33kV SYSTEMS ARWE
CALLED UNEARTH SYSTEMS AND THIS SYSTEM IS VERY STABLE
COMPARED TO DIRECTLY GROUND SYSTEM.
| Is This Answer Correct ? | 9 Yes | 12 No |
Post New Answer View All Answers
previous year paper of ntpc bhel for degree in electrical enng
What are your personal skills and abilities for such a Master Course and your possible preparation to undertake this course?
how to select electronic timer(Star-Delta) setting for diff. rating motors
what are types of encoder
We have drive feeding an output contactor for a 5000 hp motor @ 5kV application. The motor FLA is 629amps x 1.25% service factor = 786.25 amps The cable that we current have in place between the drive and the output contactor is 350kcmil- MV-105 (parallel cables). Per the NEC table 310.60 (C) (69). This show the cable ampacity is at 615 amps per cable for a rating of 1230 amps. We have derated the cable for the cable tray and the multiple cables application and our calculations show that after the correction factor factor we are at 922amps. 1230 amps x .75% correction factor factor = 922.5 amps. The customer is driving us to then use another safety factor of .25% off of the already derated cable. Can you please provide a longhand calculation for your solution on this application?
Explain Circuit Breaker Trip Characteristics in detail.
When we connect the large capacitor bank in series ?
What is the function of NER and NET?
What the main causes of transient interruptions on Over-Head Distribution Lines?
What is the difference between cylindrical-type and sandwich-type winding?
Define pole pitch?
WHAT IS SPEC OF CLEANROOM MOTOR AND LIGHT FITTINGS?
In electrical what is earth(ground)connection, wht is the importance of it, why it is recomended to maitain below 3VAC between Neutral and earthspecially in PLC used machines?
What happened when capacitor connect series in ac circuit?
when we have to use UPF wattmeter and LPF wattmeter? what is the difference between UPF and LPF wattmeter in terms of construction?
