IEEE C37.012-2005 pdf free.IEEE Application Guide for Capacitance Current Switching for AC High-Voltage Circuit Breakers.
This application guide for capacitance current switching applies to ac high-voltage circuit breakers rated in accordance with IEEE Std C’37.O4TM’ and listed in ANSI Std (‘37.06. It is intended to supplement IEEE Std C37.O1OTM. Circuit breakers rated and manufactured to meet other standards should be applied in accordance with application procedures adapted to their specific ratings.
1.2 Purpose
This guide is intended for general use in the application of circuit breakers for capacitance current switching. Familiarity with other American National Standards applying to circuit breakers is assumed, and provisions of those standards are indicated in this guide only when necessary for clarity in describing application requirements.
2. Normative references
The following referenced documents arc indispensable for the application of this application guide. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments or corrigenda) applies.
ANSI Std C37.06, American National Standard for AC High-Voltage Circuit Breakers Rated on a Symmetrical Current Basis Preferred Ratings and Related Required Capabilities.
3. General
Capacitive currents are encountered in the following cases:
Switching of no-load overhead lines
— Switching of no-load cables Switching of capacitor banks
Switching of tiltcr banks
Interruption of capacitive currents is generally a light duty for a circuit breaker because the currents are normally a few hundred amperes. There is, however, a probability that rcstrikcs will occur. Rcstrikcs may lead to undesirable overvoltages or high-frequency transients afTecting power quality in the network and may also cause damage to the breaking unit.
Energization of capacitive loads may lead to overvoltages or high currents. Two such cases are the switching of parallel capacitor banks and the switching of no-load lines.
The testing is designed to be representative of the service conditions up to the point of clearing, reigniting, or restriking. Because the actual value of overvoltage and transient response is totally system dependent, tests cannot replicate these effects. By providing a means of assessing the likelihood of restrike occurrence, users can determine what best suits their application. It is assumed that because capacitor switching is not the only source of overvoltage. other protection systems arc employed; and in the case of unacceptable power quality for sensitive electronic equipment, a sufliciently low number of likely events are selected. A separate study of actions relative to power quality on energization should also be made.
In the selection of the rating for the circuit breaker for capacitive current switching, the following needs to be considered:
a) Application. i.e., overhead line, cable, capacitor bank, or filter hank
b) Power frequency of the network
c) Grounding situation of the network
d) Presence of single- or two-phase-to-ground faults.IEEE C37.012 pdf free download.