what is the function of NAT & NAC contacts in breaker
control switch (TNC)??

Answers were Sorted based on User's Feedback

what is the function of NAT & NAC contacts in breaker control switch (TNC)??..

Answer / k.prakashchandra

NAT- normal after trip and NAC normal after close.These are
'lost motion contacts' which indicate last operated position
of breaker .With NAC contact we get 'Auto-trip' indication
when the breaker is tripped by relay.

Is This Answer Correct ?    9 Yes 5 No

what is the function of NAT & NAC contacts in breaker control switch (TNC)??..

Answer / rajesh t k

The NAT and NAC contacts are provided on TNC switch to facilitate additional functionalities from the TNC switch than mere Tripping or Closing.

These contacts are also known as Lost Motion Contacts. They help identify the last operation (Trip/Close) performed by the operator through the TNC switch.

The NAC contact will be closed whenever the operator turns the TNC lever to Close position and the contacts stays closed even after the lever is returned to the Neutral position by the operator, until the lever is turned to Trip side.

Hence, the 'Auto Trip' indication can be given via the NAC contact(instead of giving through an NO contact of the master trip relay), in series with the CB's 52b contact. That is, this is just an alternate way to wire up the 'Auto Trip' indication.

The NAT contact, likewise will be through whenever the CB has tripped via the TNC lever switch by the operator, until the lever is turned to Close position again.

Is This Answer Correct ?    1 Yes 0 No

Post New Answer

More Electrical Engineering Interview Questions

what is impedance in a transformer? how can i calculate it?

1 Answers  

if a 3 phase induction stator has charactristic plate and have on winding inside.with the calculation of plate or dimenssion of core how one can desinge rewinding drawing.

0 Answers  

What mean 150 amp hour write on battery.

1 Answers   Syncom,

how to calculate induction motor rating (HP) if name plate is missing from motor at site condition ?

6 Answers   Bhel, Voltas, apatel, ABB, Spatel,

how the fan is switched off immediately switching off the switch?

2 Answers  

What is the difference between shortcircuit current, rated current of cable & MCB with example? What will be the size of cable required for 5.5 KW motor (Full load current 10 Amps approx.), Starting current with DOL is 120 Amps. Aprrox. Short circuit current with LLLG fault is 2000 Amps Approx.

0 Answers  

How to calculate Battery back up time for a 400 AH Battery bank having a load of 20 Amps and charging time required to fully charge this battery bank?

2 Answers  

motor work in hat principle generator work in what principle transformer work in what principle pls explain with details or answered to ramadoss.sepc@gmail.com

1 Answers   Vestas,

What is principal to reduce earth leakage current with isolation transformer? When isolation transformer is installed in input stage of system, earth leakage current is reduced. the reason is why the leakage current of 2nd stage of isolation transformer does not affect the 1st stage's leakage current. I would like to know the reason. As you know, earth leakage current is a kind of AC. So, How to reduce earth leakage current in case that isolation transformer is used?

2 Answers  

What does the letter CTNM in negative phase sequence relay means?

0 Answers  

can you explain the rms value in simple words....

5 Answers  

Is it possible to make 0.75KW motor earthing from MCC panel by using the 1.5 SQMM, 4 core cable, means 3 core for 3 Phases & 1 core for Earth terminal?

4 Answers  

  • Civil Engineering Interview Questions Civil Engineering (5064)
  • Mechanical Engineering Interview Questions Mechanical Engineering (4645)
  • Electrical Engineering Interview Questions Electrical Engineering (16567)
  • Electronics Communications Interview Questions Electronics Communications (3716)
  • Chemical Engineering Interview Questions Chemical Engineering (959)
  • Aeronautical Engineering Interview Questions Aeronautical Engineering (214)
  • Bio Engineering Interview Questions Bio Engineering (96)
  • Metallurgy Interview Questions Metallurgy (361)
  • Industrial Engineering Interview Questions Industrial Engineering (272)
  • Instrumentation Interview Questions Instrumentation (3005)
  • Automobile Engineering Interview Questions Automobile Engineering (332)
  • Mechatronics Engineering Interview Questions Mechatronics Engineering (105)
  • Marine Engineering Interview Questions Marine Engineering (151)
  • Power Plant Engineering Interview Questions Power Plant Engineering (170)
  • Textile Engineering Interview Questions Textile Engineering (473)
  • Production Engineering Interview Questions Production Engineering (0)
  • Satellite Systems Engineering Interview Questions Satellite Systems Engineering (106)
  • Engineering AllOther Interview Questions Engineering AllOther (1376)