Answer / praveen kumar gupta

4mA is the minimum operating current of controling device

Answer / vaseekaran

Let us keep the value as 0 to 20 mA,
The valve we measure in the output will be zero if the meter is in idle state and also it will show the same zero even the instrument is in fail condition.so we cannot get the exact and get confused if there is a problem in instrument while cross checking.this is the reason we are using 4 to 20mA.if the instrument fail then we can get only zero and if the instrument is idle we will get 4mA.so we can easily differentiate it.

Answer / raja

There is a long tradition dating from the early pneumatic
instruments for a control range from 25% to 100%. If you
want to know why, look at the pressure vs travel curve for a
flapper-nozzle. The early electronic instruments used the
same force-balance approach (many with a 10-50 mA range -
easier to get a higher force with the higher current) which
was eventually translated over into the pure electronic format.

what is meant by reactive power ?

5 Answers  

---

WHY DO VOLTAGE TRANSFORMERS FAIL DURING EARTH FAULT IN THE DELTA CONNECTED 6.6KV ELECTRICAL SYSTEM

0 Answers  

---

Hi,Any one has idea regarding the KPTCL Recuirtments for AE'e & JE's for the year of 2009-10???Kindly help in regards..

6 Answers  

---

state the functions of different parts of star delta starter.

1 Answers  

---

A motor works on 30 killo watts.how much ampers will be required if it works on 440volts?

5 Answers  

---

if i get a drop in my 1st year and the i clear my 2nd year and 3rd year all clear and i dont have any back logs so can i be able to sit in campus selection??

0 Answers  

---

Can we use a absolute encoder to show rpm of a motor ? what about the condition when power is off ? what is difference if a incremental one is used ?abanirout@gmail.com

0 Answers  

---

At the starting of dc motor and syn.motor and induction motor high current flowing through the winding. Due to this the windings burnt out. To avoid this different types of starters are used. But incase of transformer what Will be used (At starting no emf is induced in the primary winding)?

0 Answers  

---

What are the disadvantges of leading power factor

5 Answers  

---

A 100 KW GENERATOR , only 50 kw load is connected then how much power generated by generator

3 Answers  

---

what is p.s impedance measurement test in earthing transformer?

0 Answers   Greenko,

---

How to design CT for connected with Transformer OLTC operation? normally CT output design for 1A/5A range but during OLTC Tap position changing time how to function the CT?

1 Answers   HEG,

---