111 to 115
111. What is ferrantic effect?
Output voltage is greater than the input voltage or receiving end voltage is
greater than the sending end voltage.
greater than the sending end voltage.
112. What is meant by insulation voltage in cables? Explain it?
It is the property of a cable by virtue of it can withstand the applied voltage
without rupturing it is known as insulation level of the cable.
113. Why we do 2 types of earthing on transformer (i.e. :) body earthing & neutral earthing, what is function. i am going to install a 5oo kva transformer & 380 kva DG set what
should the earthing value?
The two types of earthing are Familiar as Equipment earthing and system
earthing. In Equipment earthing: body (non-conducting part) of the equipment should be earthed to safeguard the human beings. System Earthing: In this neutral of the supply source (Transformer or Generator) should be grounded. With this, in case of unbalanced loading neutral will not be shifted.so that unbalanced voltages will not arise. We can protect the equipment also. With size of the equipment (transformer or alternator) and selection of relying system earthing will be further classified into directly earthed, Impedance earthing, resistive (NGRs) earthing.
earthing. In Equipment earthing: body (non-conducting part) of the equipment should be earthed to safeguard the human beings. System Earthing: In this neutral of the supply source (Transformer or Generator) should be grounded. With this, in case of unbalanced loading neutral will not be shifted.so that unbalanced voltages will not arise. We can protect the equipment also. With size of the equipment (transformer or alternator) and selection of relying system earthing will be further classified into directly earthed, Impedance earthing, resistive (NGRs) earthing.
114. What is the difference between MCB & MCCB, Where it can be used?
MCB is miniature circuit breaker which is thermal operated and use for short
circuit protection in small current rating circuit. MCCB moulded case circuit breaker and is thermal operated for over load current and magnetic operation for instant trip in shortcircuit condition. Under voltage and under frequency may be inbuilt. Normally it is used where normal current is more than 100A.
115. What is use of lockout relay in ht voltage?
A lock-out relay is generally placed in line before or after the e-stop switch so the power can be shut off at one central location. This relay is powered by the same electrical source as the control power and is operated by a key lock switch. The relay itself may
have up to 24 contact points within the unit itself. This allows the control power for
multiple machines to be locked out by the turn of a single key switch.
have up to 24 contact points within the unit itself. This allows the control power for
multiple machines to be locked out by the turn of a single key switch.
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