Interested to Buy Any Domain ? << Click Here >> for more details...
What is IDMT relay how it works.
- 3 Answers
- 89840 Views
- Electrotherm, Sulzer, I also Faced
- E-Mail Answers
Answer Posted / venu
The over load inverse time relay . It consists of an upper
electromagnet that has been provided with two windings one
primary and the other secondary. Primary is connected to a
current transformer in the line which is under protection
and is provided with eight tappings. These tappings are
connected to a plug setting bridge by which the number of
turns to be used can be adjusted in order to have the
desired current setting. The second winding called
secondary is energized by the induction effect and is wound
over the central limb of the upper magnet as well as it is
spread over the two limbs of the lower magnet. By this
method, the leakage flux from the upper magnet entering the
disc have been displaced in phase from the flux entering
the disc from the lower magnet. The deflecting torque is
produced on the disc in the fashion as already explained.
The spindle of the disc carries a moving contact which
bridges two fixed contacts after the disc has rotated
through a certain angle which has been set before. Any
setting for this angle is possible varying from 0 to 360°.
The variation of this angle imparts to the relay, various
time settings.
The speed of rotation of the disc is dependent upon the
torque which in turn is dependent on the current setting,
when the load current increases from this setting it will
increase the speed of rotation of the disc resulting into
decrease of operation time. Thus the time current
characteristics of the relay observe inverse-Square law.
The definite minimum time characteristics of the relay are
obtained by the use of a saturated upper magnet. This
ensures that there is no further increase in f1ux when the
current has reached a certain value and any further
increase of current will not affect the relay operation.
This results in a flattened current time characteristic and
the relay obtains its name as Inverse definite minimum time
lag (I.D.M.T.) relay
The current time characteristics of the relay It represents
the time required to close the trip contacts for different
values of over current. Its horizontal scale is marked in
terms of current-setting multipliers i.e. number of times
the relay current is in excess of current setting
| Is This Answer Correct ? | 97 Yes | 17 No |
Post New Answer View All Answers
What is a dc motor?
Is it required to lay 2 runs of GI wires along with armoured cables from one power DB to another Power DB?
hello!my name is sheikh iam preparing for indian engineering servieces,please send me the old question papers..to sheikhshaazforjobs@gmail.com
In radial network the source is fed from 1 end both ends at central
Why it is possible to use PWM with a STATCOM and not with a conventional TCR based SVC
How can we calculate the motor frame sizes?
What is the ratio of Booster transformer?
what is rocking arrangement in arc heating
In AC if the direction of current keeps reversing every half cycle, how does it propogate through the transmission lines?
What happens to voltage when current is zero?
sir my exam is on 19/6/2013 under electrical branch pls send me sample aptitude questions as well as sample technical questions for jindal steel and power company
what is efficient motors and how it is different from normal induction motors
how do u gauge the size of the cable ?for eg. consider a 300 sqmm L.T Cable.How do u determine the size of the cable seeing it pratically?
Is it true online ups having bypass mode if it is true then why we called ups because it is interrupting power when goes in bypass mode
How to set the relay,,??
