| 摘要 |
704,191. Electric indicating systems. RECORD ELECTRICAL CO., Ltd., and LOMAX, S. Sept. 19, 1952 [Sept. 21, 1951], No. 22159/51. Class 40 (1). A ratio meter for indicating the percentage slip between two rotating members driving tacho-generators G1, G2, has a current coil energized according to the difference output voltage of the two generators, and a pressure coil energized by one or both of the outputs whereby the meter indicates the speed of one member as a percentage of the speed of the other or the slip as a percentage of the average speed. In Fig. 1 the speed of generator G2 is indicated as a percentage of that of G1, the pressure coil A being energized by generator G1 and the current coil B being series connected with the two opposing generator outputs. Resistors R1, R2 equalize the loads on the two generators. A centre-zero type meter is used so that it will indicate the sense of the slip. Fig. 2 shows the pressure coil A connected via equal resistors R1, R2 across both generators so that the slip relative to the average speed of the generators is indicated. In another arrangement the speed of G1 is compared with a fraction of that of G2 by connecting the range determining resistor R3 to a tapping or a potentiometer connected across G2, Fig. 3 (not shown). The resistor R2 may be adjustable, Fig. 4 (not shown), to compensate for changes in the generated voltages. For a precise indication of zero-slip a lamp L, Fig. 5, is connected, via isolating condensers C, across the generator outputs to indicate the beats between the ripple outputs of the generators. These beats may be timed by a stop watch for small values of slip and disappear at zero slip. The range may be extended, Fig. 6, by a relay S connected across the generators which shortsout resistors R1b, R2b, R3b, when the average speeds drops below a predetermined level. Additional relay stages to extend the range further may be used. |
