advanced search

Quick Disconnects Speed Motor Changeouts

Jul 1, 1998 12:00 PM, By Jerry Woodward, Thomas & Betts Corp.

Unique device has contact rings with high conductivity and high contact force.

Many facilities have dozens, possibly hundreds, of motors, some driving a variety of equipment or even continuous-operation machines and systems. Because downtime on many processes is so costly, a fast changeout of a faulted motor is an important advantage. At the Ponderay Newsprint Co., Usk, Wash., some connectors and boots simplify and speed motor changeouts. With motor maintenance and troubleshooting maximized, modern quick disconnects and insulating boots save time and money.

Motors, motor controllers, and related equipment should receive regular preventive maintenance and testing. Usually, we perform these tests with test instrument probes connected at the motor controller. If necessary, you can quickly isolate the controller from a motor with the quick-disconnect arrangement.

Plant electricians at the Ponderay facility find quick disconnects install much more quickly than the wire connector/tape method. This is because you can easily assemble the quick-disconnect terminating components, permitting much more space in the motor terminal box. The insulating boots provide a fast, clean insulation, because you can apply or remove them with such ease.

Five years ago, Charles Green, manager of electrical service, chose the disconnects to speed installation of more than 800 460V motors. Since the project's completion, there have been no termination failures or reports of "hot" connections. And because high motor reliability is essential, infrared tests of all mill motor connections, which are done every nine months, reveal only normal, reliable terminations. The selection of the quick disconnects proves to be the best choice.

Quick-disconnect system. This system consists of two- and three-part connectors (see Photo 1, original article). These connectors snap and unsnap easily, yet form a highly reliable connection; even after numerous connect and disconnect operations.

The quick-disconnect motor connectors come in sets that accommodate one line to one load (two wires); or one line to two loads (three wire). Four "body sizes" allow matching of different wire sizes, because line supply cables are often larger than the motor leads. For example, you can properly connect a No.12 motor lead wire to a No. 1 supply line cable with one particular body size, or a No. 2 motor lead to a 4/0-supply cable with another body size.

These connectors offer numerous advantages over conventional motor lead connectors. They eliminate nuts, bolts, washers, torquing procedures, and the danger of mismatching bolt-holes on-line and load cable lugs. They save a great deal of labor time.

Contact ring improves conductivity. The quick connector is dependable because of a high-amperage capability of an interface ring or band. This band, which occupies the female portion of the connector, has raised louvered edges, tin-plated for low contact resistance. (See Photo 2, on page 50 of original article). The band is made of beryllium copper, which creates its high conductivity. It also has excellent spring characteristics, aiding the reliability of the termination.

When you insert the male pin into the female socket containing the contact band, all the raised edges of the louvered band are deflected, producing a multitude of high-force contact points. Each contact point is typically in the force range of 8000 psi to 10,000 psi. High currents, caused by short circuits or sudden surges, tend to make the interface even more efficient by increasing the contact pressure.

Multiple high-force contacts are more efficient electrically than two flat surfaces bolted together. For example, two lugs bolted together generally produce good contact only in the immediate area of the bolt-holes. You can install the connectors using a mechanical crimping tool, creating a larger area of high-pressure contact between the cable, motor lead, and connector. This assures low resistance and high pullout strength.

Boots add reliability. Insulating boots protect the connectors. This eliminates taping and "knuckle-busting" work in tight spaces. The boot and connector are also more compactthan two lugs bolted together and taped. Installing the boot takes only seconds, versus up to 10 min for taping. Unlike tape, the insulating boot is reusable. It slips on and off quickly and easily.

In cases where dirt, corrosion, condensation, and humidity are a problem, you can add a tape sealant over the connectors before you install the boot. Supplied in 10-ft rolls, the tape sealant is removable and reusable.

The insulating boot, (see Photo 3, original article) also eliminates an installation variable: the skill of the installer assigned to tape the connection. Moreover, there is less chance of failure due to insulation breakdown from heat and vibration. When disconnecting the leads, the boot also eliminates cutting away of insulator tape. Since a knife isn't used, motor leads can't be damaged.

Want to use this article? Click here for options!

© 2012 Penton Business Media, Inc.

---

Acceptable Use Policy blog comments powered by Disqus

Browse Back Issues Select an Issue EC&M Magazine | April 2012 March 2012 February 2012 January 2012 December 2011 November 2011 October 2011 September 2011 August 2011 July 2011 June 2011 May 2011 April 2011 March 2011 February 2011 January 2011 December 2010 November 2010 October 2010 September 2010 August 2010 July 2010 June 2010 May 2010 April 2010 March 2010 February 2010 January 2010 December 2009 November 2009 October 2009 September 2009 August 2009 July 2009 June 2009 May 2009 April 2009 March 2009 February 2009 January 1, 2009 December 2008 November 2008 October 1, 2008 September 2008 August 2008 July 2008 June 1, 2008 May 2008 April 2008 March 2008 February 2008 January 2008 December 2007 November 2007 October 2007 September 2007 August 2007 July 2007 June 2007 May 2007 April 2007 March 2007 February 2007 January 2007 December 2006 November 2006 October 2006 September 2006 August 2006 July 2006 June 1, 2006 May 1, 2006 April 2006 March 1, 2006 February 2006 January 2006 December 2005 November 2005 October 2005 September 2005 August 2005 July 2005 June 2005 May 2005 April 2005 March 2005 February 2005 January 2005 December 2004 November 2004 October 2004 September 2004 August 2004 July 2004 June 2004 May 2004 April 2004 March 2004 February 1, 2004 January 1, 2004 December 1, 2003 November 1, 2003 October 1, 2003 September 1, 2003 August 1, 2003 July 1, 2003 June 1, 2003 May 1, 2003 April 1, 2003 March 1, 2003 February 1, 2003 January 1, 2003 December 1, 2002 November 1, 2002 October 1, 2002 September 1, 2002 August 1, 2002 July 1, 2002 June 1, 2002 May 1, 2002 April 1, 2002 March 1, 2002 February 1, 2002 January 1, 2002 December 1, 2001 November 1, 2001 October 1, 2001 September 1, 2001 August 1, 2001 July 1, 2001 June 1, 2001 May 1, 2001 April 1, 2001 March 1, 2001 February 1, 2001 February 1, 1995 January 1, 2001 December 1, 2000 November 1, 2000 October 1, 2000 September 1, 2000 August 1, 2000 July 1, 2000 June 1, 2000 May 1, 2000 April 1, 2000 March 1, 2000 February 1, 2000 January 1, 2000 December 1, 1999 November 1, 1999 October 1, 1999 September 1, 1999 August 1, 1999 July 1, 1999 June 1, 1999 May 1, 1999 April 1, 1999 March 1, 1999 February 1, 1999 January 1, 1999 December 1, 1998 November 1, 1998 October 1, 1998 September 1, 1998 August 1, 1998 July 1, 1998 June 1, 1998 May 1, 1998 April 1, 1998 March 1, 1998 February 1, 1998 January 1, 1998 December 1, 1997 November 1, 1997 December 1, 1996 November 1, 1996 October 1, 1996 September 1, 1996 August 1, 1996 July 1, 1996 June 1, 1996 May 1, 1996 April 1, 1996 March 1, 1996 February 1, 1996 January 1, 1996 December 1, 1995 November 30, 1995 November 1, 1995 October 1, 1995 September 1, 1995 August 1, 1995 July 1, 1995 June 1, 1995 May 1, 1995 April 1, 1995 March 1, 1995

browse e-newsletters