Answer / ashish

its a type of overcurrent - earth fault relay --
IDMT -- inverse definite min. time , having diff types--
normal inverse / long inverse / short inverse type

the relay are of 3 types
1) electro mechanical (whose opeartion way is described by
others)
2) static and latest are 3) numericals --no moving part.

the simple way to explain its principle is that
THE RELAY OPERATIONAL TIME IS INVERSELY PROPORTIONAL TO
THE FAULT CURRENT. IN NORMAL INV IDMT FOR A 2.0 TIMES
CURRENT WITH TMS (TIME MULTIPLIER SETTING) of 1.0 THE RELAY
OPERATInG TIME IS 10 SEC,.. WHEREAS FOR THIS SAME SETTINGS
IF CURRENT IS DOUBLED THE TIME REQUIRED IS ALMOST 5 SEC..

but after 20 amp(in 1 A relay) the time reqd is same.

Answer / ajay k mathew

Inverse Definite Minimum Time relay.aluminium or copper disc rotate b/w electromagnet and damping magnet.fluxes induce eddy currents and interact to produce torque.disc rotate to a point where it operates a pair of contact and remove fault

Answer / santhosh.9289

the current in the main winding produces magnectic field that displaced to closing winding,auminium disc produces eddy current that disc make rotate.as the current disc of rotation is high minimum time of operation

DEAR SIR, HOW TO CALCULATE WELDING TRANSFORMER CAPACITY IN KW OR KVA (POWER). TWO WELDING TRANSFORMER USED WHAT TYPE OF DG SET CAPACITY LIKE ( 45 KVA OR 62.5 KVA), PLEASE TELL THE WELDING TRANSFORMER RATEINGS. I AM REFINARY (TANKS WELDING) THANKING YOU

2 Answers  

---

what is the mean of short circuuit current ( for ex. 50KA)?

2 Answers   Weltech Engineering,

---

what is CT class? depending upon which it is classified?

3 Answers   Siemens,

---

At the time of 1st charging of transformer, there were huge inrush current, so why at that diffrential relay are not operated? Why?

3 Answers   Adani,

---

What is the difference between in Fourier series and Fourier Transform. and please tell me the difference between both of them and the why we use them in communication system?

0 Answers  

---

WHAT IS SITTING AMPS IN OVER-LOAD RELAY FOR 1PH OR 3PH MOTORS?IF ITS NAME PLATE GIVEN MAX AMPS 10AMPS?

0 Answers  

---

What is CRT (Contact Resistance Test) for Isolators or Dis- connector Switches? Why we performed it & whats the Testing procedure.

1 Answers   Siemens,

---

What is fault.?

2 Answers   AngloGold Ashanti, MNC,

---

What are the role of each components in PID COntroller

1 Answers   BARC,

---

What is the safe limit of voltage between earth and neutral in india.

2 Answers   Incepta Pharmaceuticals,

---

how can we chack a capacitor in acircuit

2 Answers  

---

Current chopping mainly occurs in air blast circuit breaker.why?

1 Answers  

---