What is the minimum setting in REF relay because i am
facing some problem whenever power resumes after power
failure my transformer is tripping because of REF trip. I
am using CSPC make numerical relay(DIP switches). Now
setting is 15 percentage. What is the reason for this
triping. I sm waiting for answer

Answer Posted / k.prakashchandra

Your setting is 15% of In.While charging ,Tr draws initial
magnetizing current 6 to 15 times the In. Any difference in
measurements by CT s at this current ,may exceed the set
current.Even 1% error in measurement at normal current
becomes 15% of In at initial charging current at 15 times
the In

Is This Answer Correct ?    0 Yes 1 No



Post New Answer       View All Answers


Please Help Members By Posting Answers For Below Questions

How can I known multiplying factor .without multiplying table

1362


how the inner and outer body is separated in aircrafts?

603


Hi guys! Plz help me to answer the following questions. 1. What are the types of transmission line energy losses? 2. Why are the VLF are used some types of services? 3. What frequencies are used for reliable beyond the horizon terrestrial communication without repeaters? 4. To permit selection of 1 out 16 equi-probable, what is the number of bitis required? 5. What is the most common modulation used for telegraphy? 6. What is the multiplexing is used to increase the capacity of the optic fiber? Thanks

1628


Will an earth leakage trip be activated if the component or wiring is faulty on low voltage equipment.Example An electrical Cat Scarer placed in the garden and water gets into the wiring.

1428


How much ph is maintained of water electrolyte which is used in LRS for 1200 kw slipring induction motor ?

1258






what is the minimum winding resistance of 30hp compressor, to run or to switch on

1408


If Neutral Grounding Resistor (GR) failed/shorted. Is it repairable.

1157


Tell me in detail about c.t. And p.t. ?

733


iam preparing for rrb section engineer post in electrical branch.suggest the right textbook for my reference.fromwhere i will get the previous q.papers?

1736


In AC if the direction of current keeps reversing every half cycle, how does it propogate through the transmission lines?

1647


Where can i get practical knowledge of solar system?

977


What is force on a conductor in a magnetic field ?

626


any earth foult trip the relay but in welding time not trip by earth foult

2734


transformer spections :: input voltage 0-110-230v; output volage 0-10-12-14v; amp=3A using CRNO CORE, capcaity=50VA primary turns = ? ; secondry turns =?

1667


what is the difference between unarmoured & Flexible cable? How to identified?

5441