| 摘要 |
In the case of the power relay, a measurement voltage which is proportional to current and a measurement voltage which is proportional to voltage are produced with the aid of electronically fault-compensating converters (5, 6, 7 and 21, 22, 23 respectively). The two measurement voltages are supplied to a TDM-multiplier (18, 19, 20) in order to form the products of the instantaneous values of current and voltage. The output voltage of the multiplier (18, 19, 20) is supplied, after smoothing in a smoothing stage (33), via a range setting device (34) to a threshold value switch (35). A display and/or switching device (36, 37) is connected to the outlet of this threshold value switch. The power relay can be constructed, in particular, as a multi-phase power relay. <IMAGE>
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