| 摘要 |
The invention concerns a method and coupling for measurement of the resistance value RX of an electrical resistance 1 so that the loss power is limited. According to the method: electrical resistance 1 being measured and reference resistance 2 are arranged sequentially; reference resistance 2 is arranged at the input of reference channel 31 and measured resistance 1 at the input of measurement channel 32; at the cited resistance 1, 2 and equally large low- frequency excitation alternating current Iex is supplied; and in each channel 31, 32 the excitation voltage VX, VR is amplified via resistance 1, 2 in the same phase as the excitation alternating current Iex to the reference and measurement dc voltage Vv, Vm in the corresponding channel 1, 2; and a feedback voltage Vt1, Vt2 is recovered for pre- amplifiers 33, 39 in each channel 31, 32 at which the reference and measurement dc voltages Vv, Vm will be changed so that the feedback voltage Vt1 of the reference channel 31 and the voltage VR via reference resistance 2 and the respective feedback voltage Vt2 of measurement channel 32 and voltage VX via measurement resistance 1 correspond to each other; and in the method the reference dc voltage Vv and the measurement dc voltage Vm are compared with each other and the value of the measurement resistance 1 RX is determined by means of value RR of the comparison result and the reference resistance 2. According to the invention: the dc voltage IB is fed via both reference resistance 2 and measurement resistance 1 in addition to the low frequency excitation ac voltage Iex; the input to reference channel 31 and measurement channel 32 is arranged at the same dc voltage potential; and the measurement channel 32 is arranged to amplify only the excitation ac voltage VX that acts via measurement resistance 1. <IMAGE>
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