IEEE 300411-2019 pdf download
IEEE 300411-2019 pdf download.Recommended Practice for Bus and Switchgear Protection in Industrial and Commercial Power Systems.
The most common arrangements are single bus radial systems with or without main devices and double ended line ups with two sources, a tie, and with mains for each source. Other more complex arrangements with dual ties in series or more than two sources are also possible. in the interest of reliability, a system designer may decide to implement a system with multiple sources in multiple enclosures with tie bus separately housed to connect the equipment where the bus associated with each source is located. This kind of arrangement lends itself well to dual ties. When a system is divided into multiple individual line U5 of equipment with tie bus in between them, consideration should be given to the protection of the longer tie bus which may be more exposed than a short length of tie bus within a single piece of equipment with multiple sources. IEEE Std C37.234-2009 describes various bus schemes and associated protection zones used in MV and liv systems. The methods of protecting substation buses and switchgear might vary depending on voltage, arrangement of the buses, economic considerations, and other practical considerations.
4.2 Voltage ranges
North American industrial power system voltages fall into three categories:
— Greater than 52 kV
Above 1 kV to 52 kV (in the past 38 kV instead of 52 kV was the MV to liv transition value)
— Equal to or less than I kV
Industrial and commercial power distribution systems may include buses at 52 kV and less. Modern large industrial complexes, however, may include distribution, sub-transmission, or transmission substation buses at a higher voltage level. IEEE Std C37.234 discusses power bus configurations and associated protection schemes for I1V arrangements. Also, other IEEE standards address specific configurations where necessary. Examples of’ such configuration for interconnections between an industrial facility and its supply utility are also given in numerous references (e.g., Beckmann, et al. [[13]).
5. Zones of protection
It is critical to ensure the reliability of the protection systems including:
Dependability: The system must operate when there is a fault (identify fault location and isolate the faulted part of’ the system), and
— Security and selectivity: Only the faulted power system zone is isolated, and the remainder of the power system continues its normal operations.
Zones may have defined demarcation (e.g., transformer differential protection). Protection may be defined as primary and back up protection as established by time-current coordination (overcurrent thresholds) or other protection methods. Zones of’ protection can be identified by the sensor locations that define the zone within which a fault might be detected, or by the controlled switching elements that can clear the fault once it is detected. When multiple sensors are used for the various types of protection. proper location of the sensors can ensure that blind spots are minimized. When using the same sensor for multiple ftinctions or using sensors located within the switching devices (such as in LV circuit breakers), it is important to understand that blind spots might be created and these need to be assessed. If multiple sensors are used and they can be dedicated to different protective ftrnctions and zones, then the systems designer should strive to achieve overlapping zones of’ protection that eliminate blind spots. however, excessive overlap can negatively impact system reliability as well.
Figure 1 shows a simple radial substation with a single source. In this example. differential protection is applied using dedicated CTs that are arranged so that the differential-protection zone and overcurrentprotection overlap, and the entire bus is protected. Figure 2 shows the same substation bus protection, but only one set of CTs is used. I lere, there is no overlap. I lowever, tbr a simple topology in medium and low voltage.
protection is provided by either scheme. In a system with networked sources. CT location can create short spots that are outside of the faster protection zone, or that are inside multiple protection zones, and can cause mal-operation of the protection system. For a more thorough discussion of network applications, see 5.1 of IEEE Std C37.234-2009.
