Faraday current sensors using a variety of sensing elements have been investigated extensively for their high sensitivity as well as other advantages [G.L. Lewis et al., Proc. IEE Conf. on The Reliability of Transmission and Distribution Equipment, 1995; Y.N. Ning et al., Optics Lett. 16 (1991); C.M.M. van den Tempel, Appl. Optics 32 (1993)]. Concurrently chromatic modulation techniques have been investigated at the University of Liverpool for use with optical fibre sensors of different types [N.A. Pilling, Ph.D. Thesis, 1992; M.M. Murphy, Ph.D. Thesis, 1991] including Faraday current sensing, for overcoming difficulties with non-referenced intensity modulation systems. In this contribution a brief discussion of the scope of chromatically based Faraday current sensing with particular regard to electric power transmission and distribution industries is given. A novel sensor based upon a Faraday glass block in combination with a BSO crystal in the sensing element is described. The sensor takes advantage of the natural gyrotropy of the BSO which conversely has been previously regarded as a disadvantage. The experimental results obtained indicate that this method offers a novel approach to improving system sensitivity. The extension of the approach from a simple bench top demonstrator to real power systems deployment is also discussed.
[1]
Albert Feldman,et al.
OPTICAL ACTIVITY AND FARADAY ROTATION IN BISMUTH OXIDE COMPOUNDS
,
1970
.
[2]
P. C. Russell,et al.
Chromatic modulation based metrology
,
1993
.
[3]
G. R. Jones,et al.
A tap-changer monitoring system incorporating optical sensors
,
1995
.
[4]
M. Deeter,et al.
Temperature dependence of the Verdet constant in several diamagnetic glasses.
,
1991,
Applied optics.
[5]
C. Tempel.
Model of a new temperature-compensated optical current sensor using Bi 12 SiO 20
,
1993
.
[6]
E. Lewis,et al.
Optical fibre based sensing using chromatic modulation
,
1987
.
[7]
David A. Jackson,et al.
Miniature Faraday current sensor based on multiple critical angle reflections in a bulk-optic ring.
,
1991,
Optics letters.