GB191869A - Improvements in or relating to combined ammeters and volt meters - Google Patents

Abstract

191,869. Morris, W. B. Oct. 31, 1921. Electromagnetic current meters; combinations of instruments.-A combined ammeter and voltmeter is arranged so that the same scale divisions can be used alternatively to indicate amperes or volts, means being provided whereby either the ammeter or voltmeter circuit of the instrument can be excited. As shown in Fig. 1 the scale is of the centralzero type and is arranged to indicate the charge or discharge current of an accumulator. As shown in Fig. 3, the ammeter circuit d, of heavy gauge wire is wound upon a spool c and has its end connected to terminal members h, i. The voltmeter circuit g, of relatively fine wire is wound upon the ammeter circuit d, and the two circuits may be interconnected by making the teiminal h common to both. A high resistance winding upon a spool x, disposed below the main spool c, may be connected in series with the voltmeter winding at the end leading to a terminal j. The alternative circuits may be connected for their respective purposes by means of a two-way switch. The spool c is supported by an L-shaped lug p formed by cutting two parallel slits o, o in the circular rear plate k of the instrument and bending the tongue thus formed twice at right-angles in an upward direction. The upper end of the lug p carries a bearing which supports one end of the spindle t carrying the armature b and pointer a. The spool c is preferably oval or elongated in crosssection, and is partially encircled by a perman-- ent magnet e providing a controlling means.