How can you calculate in detail the VA burden of current
transformer used for Restricted earth fault protection?
Please understand that the CT required here is Class PX or
X. Also please show the calculations for knee point vtg,
stabilizing resistor, magnetising current.
Answer Posted / william lobo
Knee Point voltage is nothing but a point at which the CT
saturates. Thats why its always better to design the CTs
which can operate without saturation even at a voltage
appears in the CT during fault condition. Pls find below
the following formula for calculating the Knee point
voltage.
Vk=2If(Rct+2Rl).
where, If is the current refected to the CT secondary
during fault condition,
Rct is the resistance of the CT which can be adopted by
means of a thumb rule considering the CT ratio,
Rl is the lead resistance i.e. sum of the resistance of the
wire connected between the relay & CT and Impedance offered
by the internal circuitary of the relay
For PS class CT's designed considering the above,burden is
not applicable.
| Is This Answer Correct ? | 7 Yes | 0 No |
Post New Answer View All Answers
How to minimize the eddy current losses?
Why there are some equipment(i.e:TV) that using 2-pin plug instead of three? What happen if there is current leakage? Are we going to get electric shock??
how can service sitting be setted for MCCB?Example for sittings IR (CURRENT RATING),IS(CURRENT STARTING)IO (current operating)?
what is the difference between interconnection and intraconnections in the circuit diagrams
define hysteresis loss, eddy current loss and windage loss
what is the function of choke in the flourcent tube lights and why the colour is in white mostly in flourcent tube lights
What are the special cables required for explosion proof wiring?
placing earthing pit in pathway is correct or wrong??. placing earthing wireGI1/18 inside walls is correct or wrong?. explain!!!
why transformer tank is in rectangular shape what happen when it is in step shape
why high speed tripping relay is used in protection circuit why not normal relay
How to dimensioning SDCCH, LAPD and CS7 signaling on GSM?
Difference between field rheostat and armature rheostat.
What is ferro-resonance in electrical system? Why it occurs and what are measures to prevent it?
why swinburnes test cannot be performed on series machines?explain
what parameters are should nessary for control technic dc drive(in rolling mills)?