The similar Varley loop uses fixed resistors for RB1 and RB2, and inserts a variable resistor in the faulted leg. Test sets for cable testing can be connected for either bridge technique. If the fault resistance is high, the sensitivity of the Murray bridge is reduced and the Varley loop may be more suitable.
"Science Links Japan | Development of Murray Loop Bridge for High Induced Voltage". sciencelinks.jp. Archived from the original on February 17, 2012. https://web.archive.org/web/20120217004355/http://sciencelinks.jp/j-east/article/200324/000020032403A0828577.php ↩
https://www.jstage.jst.go.jp/article/ieejpes/123/11/123_11_1411/_pdf Development of Murray Loop Bridge for High Induced Voltage (PDF) [2509K] (Japanese) https://www.jstage.jst.go.jp/article/ieejpes/123/11/123_11_1411/_pdf ↩
Latimer Clark, Robert Sabine Electrical tables and formulæ: for use of telegraph inspectors and operators, E. & F.N. Spon, 1871 pp. 41-44 ↩