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

how can I check HT cable ?

2 Answers  

---

what is the meaning of x,m,k in the relays?

0 Answers   ITC Infotech,

---

can we use 7volt DC BATTERY to run a 60watt motor by stepup? Give reason for your answer?

5 Answers  

---

Why voltages are 11kv 33kv why not others?

2 Answers  

---

PLEASE SEND ME NTPC RELATED INFORMATION LIKE WHICH TOPICS HAV MORE SCOPE,BOOKS TO READ,CUT OFF...PLEASE.mail at thiru.1203@gmail.com

0 Answers  

---

---

What is difference between Dy11 & Dyn11 vector group transformer. Can both these transformers operate in parrallel.

5 Answers   Jaypee, JOY,

---

Give some example of fault limiting devices?

0 Answers  

---

what is the difference between fault current ant short circuit current?

0 Answers   LG Soft,

---

Why? We r used 50sq. mm. And above size cable in 3.5 core and below size are used in 4core

2 Answers  

---

Why reactive power is needed in a power system? How is it being absorbed or delivered by alternators? For reactive power control we are changing excitation but reactive power absorbing or delivering related to stator. How these two are interlinked? i want a detailed explanation with necessary expressions and figures?

0 Answers   Power Plant,

---

Where burned of electricity,when,who, & why.

0 Answers   NIGP,

---

As we know multiplicity factor derivation equation is as below MF = main c t ratio / main p t ratio * meter c t ratio / meter p t ratio * meter dial constant Where in digital meters for HT kwh import export now a days meter constant are calibrated already which is 1 So my question is For HT 11kv 110 v line values are as below Main c t and p t ratio are 11000 v and 110 v and 20/5 means 20 amp and 5 amp Now meter values are 11000/√3/110√3 and primary and secondary amp are displayed as -/5 amp on kwh meter so what will be the MF for this meter ?

1 Answers   NEPC,

---