IEEE C37.015-2009 pdf download IEEE Guide for the Application of Shunt Reactor Switching
2.General application conditions
2.1 Maximum voltage for application
The continuous operating voltage should not exceed the rated maximum voltage for the circuit breaker
2.2 Frequency
The rated power system frequency (f) is 50 Hz or 60 Hz
2.3 Shunt reactor load current
The capability of circuit breakers to interrupt inductive currents is generally not a concern. The circuitbreaker typically will interrupt the current at the first current zero after contact parting but may not beimmediately capable of withstanding the high magnitude recovery voltages that can then appear across thccontacts. This can result in a reignition followed by an additional loop of rated frequency current andsuccessful interruption. Refer to 2.5.
2.4 Interrupting time
The interrupting time of a circuit breaker is the interval between cnergization of the trip coil and theinterruption of the current in all poles on an opening operation. Refer to 2.3 and 5.8.
2.5 Transient overvoltages
An important consideration for application of circuit breakers for shunt reactor current switching is thetransient overvoltages generated on interruption of the current and by subsequent reignitions. Refer to
Clause 3.
2.6 Fault interrupting capability
Fault interrupting capability may not be required for all shunt reactor switching applications. If faultinterrupting capability is not a requirement, the short-time current rating of the circuit breaker should equalthe fault level applicable to the shunt reactor location.
2.7 Frequency of operation
Shunt reactors are switched frequently, often daily, to control and compensate for changes in systemloading and configuration. In the selection of a circuit breaker for this duty, consideration should be givento this matter (i.e, by specifying a circuit breaker with extended mechanical endurance).
3. Shunt reactor switching conditions
3.1 General
Three specific shunt reactor switching cases are considered in this guide. The case of directly groundedreactors is treated in detail. The cases of ungrounded reactors and reactors grounded through a neutralreactor are treated in terms of relating to or deviating from the directly grounded reactor case.
Given that shunt reactor switching is interactive, the characteristics of the reactor and the circuit have to beconsidered. Shunt reactor characteristics are discussed in Annex A, whereas applicable system and stationcharacteristics are discussed in Annex B.
The general derivation of chopping and reignition overvoltage values. discussed in 3.2 through 3.4. is givenin Annex C, whereas Annex D discusses the oscillation modes associated with the current interruption andreignition process.
Annex E, complemented by Annex F, describes how laboratory test results can be used to calculate circuitbreaker performance and expected overvoltages in actual shunt reactor installations.
Annex G contains a list of the variables used in the document.
3.2 Directly grounded reactors
The switching of directly grounded reactors can be analyzed using the equivalent single-phase circuitshown in Figure l. Basically, circuit breakers have no difficulty interrupting shunt reactor current; in fact.the current is forced prematurely to zero, a phenomenon referred to as current chopping. However, thechopping of the current and subsequent possible reignitions can result in significant transient overvoltages.