IEEE 1036-2010 pdf download

IEEE 1036-2010 pdf download.IEEE Guide for Application of Shunt Power Capacitors.
The continuous-current rating of switchgear used for capacitor bank switching may be a factor in choosing the capacitor bank size. The rating is usually determined by multiplying the nominal capacitor current by 1.25 for ungrounded capacitor banks and by 1.35 for grounded-wye capacitor banks. Where currents with substantial harmonic components are likely to be encountered, provision should be made for additional current-carrying capacity in the circuit breakers, fuses, and other auxiliary devices. More detailed information is available in IEEE Std C37.04-1999, ANSI C37.06-2009, IEEE Std C37.012-2005, ANSI C37.66-2005, and IEEE Std 1247-2005.
4.2.2 Minimum size
While there is no absolute minimum capacitor bank size, the practical minimum capacitor bank size may be influenced by the following factors:
a) The type of capacitor bank used: externally fused, internally fused, fuseless, etc.
b) The easily available ratings of capacitor units
c) Capacitor bank unbalance considerations
d) Fuse performance and/or coordination
e) The cost of the required switchgear and protection
The principal concerns when installing a small capacitor bank are the proper performance of the proposed capacitor bank (including the protection) and the cost of the installation. Under some circumstances, the cost of the installation may be reduced by installing the capacitor on a lower voltage bus in the same substation.
4.3 Control considerations
Capacitor banks are either switched or fixed, i.e.. not switched. Generally, in determining the type of capacitor bank required, consider the following guidelines:
a) Fixed capacitor banks arc sized for minimum load conditions.
b) Switched capacitor banks are designed for load levels above the minimum condition up to peak load.
5.2 Related capabilities
5.2.1 Operating and ambient temperatures
Capacitors are designed for switched or continuous operation in outdoor locations with unrestricted ventilation and direct sunlight under the maximum ambient temperatures for each mounting arrangement shown in Table 4.
5.2.1.1 Minimum ambient
Capacitors are designed for continuous operation and switching operations at temperatures not lower than _400 C. The capacitor manufacturer should be consulted for operation below _400 C.
5.2.1.2 Effect of temperature
It is essential that consideration be given to the arrangement of capacitors and complete equipment as an installation to provide adequate ventilation and dissipation of heat. Capacitors are designed to operate at a lower temperature rise than most other types of apparatus for the following specific reasons:
a) Unlike most other power apparatus, shunt capacitors (whether unswitched or switched) normally operate for relatively long periods of time at full load and, therefore, do not benefit from the lower average temperature rise characteristic of typical daily load cycles.
b) Capacitors are designed to operate at comparatively high dielectric stresses. The combination of these stresses with operation at high temperature for extensive periods of time will result in gradual deterioration and shortened life.
5.2.1.3 Design considerations
Capacitor ratings are based on maximum ambient temperatures with an allowance for heat dissipation by radiation and convection. The arrangement and mounting of capacitors and the conditions of installations will affect the heat dissipation and thereby limit the ambient temperature in which capacitors may be operated. Capacitors and capacitor equipment operating outdoors in direct sunlight and with unrestricted ventilation will normally operate with lower temperature rise than those operating indoors in still air. The following points arc important in relating the operating temperature of a capacitor to the conditions of installation:
a) An individual non-enclosed capacitor, such as is mounted on an outdoor pole. will dissipate heat with the least temperature rise (the heat dissipation being approximately 45% by radiation and 55% by convection).
b) The mounting of capacitors in rows side by side or in tiers, or both, increases the temperature rise because of heating of the air stream and because of reduced radiation.
c) The enclosing of capacitors in a housing or room without forced air ventilation increases the temperature rise because of reduced radiation and restriction of the natural circulation of air.