This article is about Overhead Transmission & Distribution Capacitor Banks Material Selection Guide for commercial buildings, plants and refinery projects as per international codes and standards.
Overhead Transmission & Distribution Capacitor Banks Quality Checking
| QC Before Installation – Capacitor Banks shall conform to all applicable requirements, standards, and specifications prior to release to be used as part of work. |
| Incoming Capacitor Banks shall be visually inspected for damage / defects occurred during transportation. |
| Capacitor Banks shall be checked for damage by store yard personnel prior to acceptance of shipment, unloading, or handling. No visible shipping or handling damage. (NFPA 70, NEC Art. 110.3 b and Manufacturer’s Instructions) |
| Capacitor Banks shall be new and unused. |
| Capacitor Banks shall be in accordance with the approved project-specific design drawings, diagrams, schedules, lists, databases, and associated design documents. |
Overhead Transmission & Distribution Capacitor Banks Selection Guide
The capacitors shall meet the minimum requirements below. Typical voltage, reactive power ratings and the BILs rating of capacitors for cross reference are given in Table 1. (IEEE Std 18-2002 Sec. 5.4)
Capacitors shall have continuous operation and frequent switching operations in outdoor locations with unrestricted ventilation and direct sunlight for the maximum ambient temperatures of each mounting arrangement shown in Table 2. (IEEE Std 18-2002 Sec. 5.4)
Capacitors shall be capable of both continuous operation and switching operations at a minimum ambient temperature of -40 deg C. (IEEE Std 18-2002 Sec. 5.7.2)
Capacitors shall be equipped with an internal discharge device that will reduce the residual voltage to 50 V or less within the following time limits after the capacitor is disconnected from the peak of rated voltage: (IEEE Std 18-2002 Sec. 6.3)
Single-phase capacitors shall have either one or two bushings. Three-phase capacitors shall have three or four bushings. (IEEE Std 18-2002 Sec. 6.5.1)
The bushings of outdoor capacitors shall have minimum electrical characteristics in accordance with Table 5. At elevations higher than 1800 meters (6000 ft) above sea level, and/or in locations with severe contamination, increased insulation withstand and /or creep age may be required to prevent bushing flashovers or excessive leakage current. (IEEE Std 18-2002 Sec. 6.5.2)
Terminal Size:
Outdoor capacitors shall be provided with the following types of terminals, as specified by the user:
a) Clamp connector to accommodate a minimum range of conductor sizes from Number 8 solid through Number 2 stranded, AWG, or
b) Threaded stud with 3/8″ x 16 or 1/2″ x 13 threads suitable for bolting directly to bus bars, or
c) Threaded stud with M12 or M16 (metric) threads suitable for bolting directly to bus bars. (IEEE Std 18-2002 Sec. 6.6.1)
Single bushing capacitors:
Single-bushing outdoor capacitors shall have the bushing terminal as specified under 6.6.2 and the case shall have a suitable connection point as the other terminal. (IEEE Std 18-2002 Sec. 6.6.2)
Indoor capacitors shall be provided with terminals consistent with current-carrying requirements in NFPA 70-2002. (IEEE Std 18-2002 Sec. 6.6.3)
Each (power) capacitor shall be provided with a permanent nameplate that includes, but is not limited to, the following information:
a) Name of manufacturer.
b) Unique serial number.
c) Manufacturer’s type, model, style, or catalogue number.
d) Year of manufacturer.
e) Rated reactive power.
f) Rated voltage, rms.
g) Number of phases.
h) Rated frequency.
i) BIL (if appl). For capacitors having bushings with two different BIL ratings, the nameplate shall show both BIL ratings, e.g. 150/95 KV BIL.
j) Flammability classification and volume of insulating fluid.
k) Statement that capacitor contains an internal discharge device.
(IEEE Std 18-2002 Sec. 6.7.1)
| Additional marking (decal or stick-on label) shall be visible from the ground. A blue marking shall be used to designate non-polychlorinated biphenyl (non-PCB) liquid. (IEEE Std 18-2002 Sec. 6.7.3) |
| The standard mounting hole spacing for capacitors rated 50 to 600 kvar and 2400 V or higher shall be 397 mm +/- 1.6mm between centers of 11.1 mm minimum-diameter holes. Cantilever-mounted capacitors (both brackets on one surface of the capacitor case) shall accommodate M 16 mounting bolts at 457.2 mm +/- 1.6 mm between caters. (IEEE Std 18-2002 Sec. 6.7.8) |
| Capacitors shall have provision for effective electrical bonding of the case to capacitor hangers or mounting frame. (IEEE Std 18-2002 Sec. 6.7.9) |
Colors for capacitor cases and bushings shall be light gray per Munsell Notation 5.0BG 7.0/0.4 as defined in ASTM D 1535-01. (IEEE Std 18-2002 Sec. 6.7.10)
International Codes & Standards for Transmission & Distribution Capacitor Banks
| SAES-P-100 Basic Power System Design Criteria |
| IEEE Std 18-2002 (Revision of IEEE Std 18-1992) |