Difference between bus bar and bus duct? Bus bars are actually simple conductor strips of copper using for connection between one system s ystem to another. For example transformer to panel bus ducts are enclosure of that bus bar
What is the basic basic difference of turn ratio & transformation transformation ratio for a transformer? Turn ratio is the ratio of the number of turns in the primary winding to that in the th e secondary winding. But transformation ratio is the ratio of the primary to the secondary induced voltage. In an ideal transformer both are same but in a practical transformer there is a small difference between the two as the voltage(or current) are not transferred exactly as the ratio(inverse ratio(inverse ratio in case of current transformation) of their turns ratio. But there is some error due to constructional limitations
Difference between feeder, substation, switchgear, switchyard? There are differences between feeder, substation, switchgear and switchyard. Here is what they are: Feeder: Feeders are the incoming circuits to the substation an d outgoing circuits from the substation. In a substation, there are one or more incoming feeders and one or more outgoing feeder. Switchgear: It is the combination of the circuit breaker and its protection, control, metering system including the disconnector (isolator), CTs and PTs etc. In low or medium voltage system, the switchgear components are located in the same indoor panel, but in high voltage system, circuit breakers, CT and PT are located outdoor and the control, protection and metering system are located in indoor panel. Substation: It is the overall system including the transformer, switchgears, bus bar and all other related equipment and systems. Switchyard: It is switching station with incoming and outgoing feeders but without the transformer. It is a type of substation but incoming feeders and ou tgoing feeders are of same voltage level. Sometimes, the outdoor areas of a substation where the circuit breakers are located are also called switchyard of the substation.
Why NGT or NGR used in transformer? Criteria-in order to protect the stator core from damage during internal earth fault it is necessary to limit the stator earth fault current al low as possible. It may be up to 10amp for generator. Basis for selection of NGT if generator is connected to the system through generator transformer then generator can be treated as an isolated system which is not influenced by the distribution earthing system. In this case you can select earth fault current as low as possible, but if we use NGR then in order to limit the low earth fault current size of the NGR will be increased. Due to big size of NGR we required more space & also it’s too costly. V = ir means if v constant i is inversely proportional to r exp:-to limit 10amp current , v =11kv/root 3 r = 11/root 3/10*1000 = 635.10 ohm ( very high value) for overcome on this, general practice to use a ngtr so that we can limit low earth current without any extra cost. Exp: - ngtr 11/240v to limit 10amp current current reflect on secondary side of ngtr will be = (11000/root 3/240)*10=264.6 amp. Resistor value on secondary side r =240/264.6 =0.9 ohm (approximately) which is much lower than 635.10 ohm.
Basis for selection of NGR if generator is directly connected to the system then we cannot limit the earth fault current u p to 10 amp. We have to select the earth fault current value above the residual capacitive charging current of system. Also we need to check the possibility of relay setting operation with ct ratio. For example- if ct ratio is 2000/1amp & earth fault limit current is 100amp relay selected with 10 % setting. Then that relay will see only 200amp earth fault current it will not see 100amp current. Also we cannot keep generator solidly grounded because of high earth fault current stator can damage same will happen with ht motor if it is connected to this system. So for this case we need to select the ngr with proper earth fault current
What is basic fundamental for choosing NGR or NGT for any generator neutral grounding? As we know that in Y connection there are 3 phases [R, Y&B] & a neutral. In neutral we provide a resistance & than we used to ground it. Such system called neutral ground resistance [NGR]. Why we use NGR? AS we know ideally the sum of current Ir+Iy+Ib is zero. So in normal cond ition the current which flow through neutral of Y winding is v ery low. In case of occurrence of phase to phase or phase to ground fault heavy unbalance current will be generated & that will flow through neutral. To res trict this current we provide a resistance in neutral. If we do not provide resistance in neutral & fault occurs at that time a heavy current will flow & it cause excessive heating in stator winding & i t may damage the winding. to prevent this we provided a resistance in neutral.
Earth Mat and Earth Plate? Earth Mat is a grid of earthing wires or cables co nnected together to reduce the earth resistance to an acceptable level. The Earth Plate is an earthing system localized and not distributed to discharge the excess currents. To provide earthing to the poles you mentioned then Earth mat can be economically viable solution but all that depends on the soil resistivity in the area, the best earthing system is the earth wells, where you can achieve less than one Ohm
Difference between surge arrester and lightning arrester? This is mainly a matter of semantics. Historically, the motivation for using arresters was to deal with lightning, so they were called 'lightning arresters'. But as system voltage increased, it became apparent that there could be switching-induced surges that were more damaging than lightning, so today, the preferred term is probably 'surge arrester'.
Float Cum Boost Charger ( FCBC ) Float Cum Boost Charger [ FCBC ] What is Float Cum Boost Charger [ FCBC ] ? OR About Float Cum Boost Charger [ FCBC ] FCBC : Float - Cum -Boost charger is functionally a charger. It has two operating modes first Float mode and second boost mode. Float Cum Boost Charger are used for charging batteries at substation / Power House Protection circuit and Telecom Exchange. These are used in places where the no break on Power supply is required. The float charger used in telecommunication consists of filler circuit to ensure continues power supply.
The Float part of the Charger remains in Circuit even when the power is driven from batteries. Operates on Single Phase or three Phase supply. Department of Telecommunication Best for protection circuit Power House and Sub Station etc. Designed for continuous use. The charger has two modes. Float and boost. In this float mode, the FCBC s upplies the DC load and the trickle charging current of the battery. Normally the _7. will be floated across the FCBC. Boost mode is meant for charging the battery.
Automatic charging of Battery is possible in the float mode. I n this mode, when the current drawn by the battery exceeds the set value, the charger will automatically charge mode to charge the battery. Once the battery current fails the charger returns to float mode. During mains fail, charger remains OF F and load supplied by using battery.
Function: Power House FCBC are designed to supply continuous power to the DC load and simultaneously charge the batteries connected. Input supply form 415V. AC 3 Phases or 220V. AC 1 Ph. is converted to regulate DC. The charger has two independent systems.
Normally the DC Power is supplied to be load by the Float Charger. It also supplies t rickle current to the battery to keep it healthy. It also supplies trickle current to the battery to keep it healthy. If the charging current under Float Mode exceeds a set level. Boost charger is switched ON. It supplies Quick charging current to the battery. On battery reaching the set value the Boost Charger is switched OFF.
Application: Float / Boost chargers are must in Power Substations. Generating Stations, Telephone Exchanges etc. for control / monitoring systems, tripping circuits and s upplying DC Power source.
