The Murphy ECD (earth current detector) range provided reliable and economical earth fault (leakage current) protection for both equipment and wiring.
The units used the Residual Current Device (RCD) principle: an internal core-balance transformer (CBT) detects imbalances (earth current leakages) in the monitored AC supply down to 10mA. An amplification and control circuit fixed or adjustable current levels up to 300mA (or more, when used with remote ERC series transformers below). The ECD range was available with fixed 20mS or adjustable 20mS to 2 sec response times, and either 110 or 240 VAC power supply voltages.
Production of the ECD range was discontinued in February 2008.
Discontinued range of residual current earth leakage detector relays, originally manufactured by Brian Bennett Electrical Engineering Ltd. (BBEE) and Modex Automation.
- ELD range sales bulletin (ms5621)
Standard models were the ELD2 (20mS fast response), ELD4 (slower, fixed trip times) and ELD5 (adjustable time response), but many variants and specials were also produced. The ELD range was superseded in Jan 2002 by a reduced number of standard ECD models above (also now discontinued).
A range of larger diameter core balance transformers, optionally used with ELD and ECD earth current detector relays. The ERC series was discontinued in March 2007.
- ERC sales bulletin (ms5776)