Current Limiting Reactors

#Channel2

#Old name : Current Limiting  Coil.
#Inventor : Vern E. Alden

Current limiting reactors or series reactors. Actually it is a large inductive reactance(X part) + small resistance (R part)
Current limiting reactors are series connected to the transmission/distribution line or to the feeder in order to limit the short circuit power on the load side of the reactor. The reactor limits the short circuit currents to a level which can be handled by the components installed in the electrical system( e.g. breakers,fuse,switches).
Due to linear inductance characteristics over the current range the full reactor impeadance is also maintained during system fault conditions.
Current limiting reactors is limited to large power station. Their cost is comperatively more for small power station than a suitable circuit breaker.
Its fully clear that, the short circuit current are reduced by an increase of the percentage reactance(%x) of the system.
[  percentage reactance %x = (Ix/V)*100  ]

#Why_we_need_a_reactor?

In large interconnected system, total rating of the alternators are high. When short circuit occurs, oviously short circuit current starts to flow at a high rate. For this current, suitable circuit breaker is also expensive. So we want to limit the fault current to a lower value to use a low rating circuit breaker.
So we use current limiting reactors.

#Advantage¶¶
protect apparatus from excessive mechanical stress, and overheating.

#Disadvantage¶¶
Inductive reactance becomes more. So more lag happens. Thus regulation becomes poor.

Reactors Rating:
• Continuous rated current(Irms, can      carry continuous without any   problem)
•• Rated short time current
••• Rated voltage

#design Features of Current limiting reactors:

When current reaches a high value, its reactance should not decrease on account of saturation under short circuit conditions. When fault current is so high the iron core should have large cross sectional area and it makes the reactors costly and heavy. In this place, we can use air core reactors or iron core with air gap.

#Types_of_reactors

• Shielded- designed for indoor and outdoor service, high thermal capacity, laminated iron shields or copper shields for support,oil cooled.
•• Unshielded- designed for outdoor service, upto 33 kv, concrete are used for mechanical support, air cooled.

Position Wise Classification
° Generator reactor
°° Feeder reactor
°°° Busbar reactor

#Difference between shunt and series reactors
Shunt Reactors helps us to reduce the receiving end voltage which attained a high value for ferranti effect. Series Reactors limits the short circuit value.

#Reactors_measured_in_KVA_or_MVA.
From this rating we get maximum power rating, the device can handle without burning.
Same goes with the shunt capacitor banks.
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