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Cabling, Conduit, Accessories and Signal Conditioning
News Release from: Rockwell Automation | Subject: Allen-Bradley 100Q Capacitor Switching Contactor
Edited by the Engineeringtalk Editorial
Team on 28 June 2001
Capacitor switching contactor cuts
current inrush
Rockwell Automation has introduced the Allen-Bradley 100Q Capacitor Switching Contactor, designed to switch single or multiple capacitors, safely and reliably, with a single component
Rockwell Automation introduces the Allen-Bradley 100Q Capacitor Switching Contactor, specifically designed to switch single or multiple capacitors, safely and reliably, with a single component A special module mounted on the front of the contactor, incorporates current surge limiting resistors and early make contacts wired in parallel with the main power contacts On operation of the contactor, the early make contacts ensure that the initial circuit is through the resistors, thereby limiting the inrush current
This article was originally published on Engineeringtalk on 8 Aug 2008 at 8.00am (UK)
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When the main contacts are closed, the inrush current has fallen to a level that can be easily handled.
The resistors are then shorted out of the circuit.
Two ratings are available; the 100Q-C16 has a 3-phase capacitor switching rating of 15kVAR at 400V, whilst the larger 100Q-C37 is rated at 25kVAR at 400V.
Suitable for DIN rail mounting, they are available with one N/O and one N/C, or two N/O auxiliary contacts and have all the features of the standard contactors from the popular MCS (Modular Control System) range.
Capacitors are widely used to improve the power factor of the load to which they are connected in order to reduce energy costs.
However, the switching of capacitors presents challenges to traditional air-break contactors because of the high inrush current drawn on initial switching.
This may be up to 150 times normal current for banks of contactors.
These currents can cause welding of the contactor contacts, nuisance tripping of the short circuit protective device and stresses to the components that reduce their operational life.
Traditional solutions include oversizing the contactor, using a contactor with special contact materials, and the addition of separate resistors or air core reactors.
However, all these arrangements require additional panel space and increase costs.
Efficiencies are also reduced where devices are permanently connected into the circuit.
With the introduction of the Allen-Bradley 100Q Capacitor Switching Contactor, engineers now have a simple and cost effective means of switching individual or banks of power factor correction capacitors.
100Q contactors are compact, safe and reliable, and suitable for a wide variety of applications throughout industry. Request a free brochure from Rockwell Automation ...
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