DE182962C - - Google Patents

Description

IMPERIAL

PATENT OFFICE.

In the patent 163877, class 2ie, self-regulating load resistance described, which - also as a comparative kilowatt is known, consists in the series connection of corresponding Groups of so-called "variation resistances" with one or more constant resistances. The variation resistors are usually made of iron wire in, the embodiment . the protective resistances commonly used in lamps. At a Operating voltage of z. B. 220 volts would be a kilowatt based on previous experience most appropriately from 20 resistors

“5 iron wires, each for 0.258 amps Current capacity is determined to be formed. This gives about 5.18 amps Calibration current, and since the variable resistors normally destroy about 27 volts are to remain at the ends of the constant resistance as 193 volts Measuring voltage. The product 5.18X193 gives exactly one kilowatt.

As can be seen, if

5 \ ⁷ ariation resistors of this type, which keep the current constant when the operating voltage is 10 volts too high or too low as a result of the change in their intrinsic resistance by getting into a changeable glow, a voltage normally reduced by about 27 volts at the shunt of the

to be checked prevail. With 220 volt systems, this is a reduction from the normal Measuring voltage by about 12 percent, with 110 volt systems, but by about 24 percent. Such a voltage reduction at the meter shunt will be particularly evident with the higher ones Voltages in direct current meters are not noticeable in any way, since the Counter constant is not noticeably influenced by the voltage. This also applies to most single-phase and three-phase electricity meters even Ferrari's system would see that the constant errors caused by this hardly amount to more than 1 percent. It exists but more recently also types of alternating current meters, which depend on the calibration voltage in are more dependent. About the inaccuracies in calibration that this causes counteracting this by means of "self-regulating" load resistors is an embodiment below for AC and three-phase purposes.

The new arrangement is based on the use of a 'small measuring transformer, its primary winding at the ends of the constant resistance of the self-regulating Load resistance can be applied most easily, so that ζ. B. at 110 volts Calibrations about 83 volts prevail on this transformer winding. The secondary Winding of this little transformer

now generates a voltage of normally no volts, i.e. as close as possible to the mains voltage; this corresponds to a transformation ratio of 83: 110 .: Would the Mains voltage during the calibration could also be different than 110 volts, that would be how known by the properties of the variators connected upstream of the constant resistance the measurement voltage untransformed almost invariably 83 volts; accordingly would also the voltage increased by transformation is always almost mathematically accurate 110 volts remain despite the occurrence of voltage fluctuations in the network. The same thing is analogous with other operating voltages with suitable '- with the low one Of course only shunt consumption

■ very small - measuring transformers, ζ. Β. at -220 volts, easy to perform; in the latter Case is the transformation ratio z. B. 193: 220 volts. The advantage of the procedure is there so not only in the fact that compared to the calibration by means of self-regulating load resistance without transformation the normal voltage acts instead of a lowered one on the meter shunt, but also in the event that any abnormal tension and shunt excitation also with the usual instruments performed with wattles or similar instruments Calibration errors caused by calibration are eliminated here, since the voltage is almost unchanged with 110, 220 volts etc. acts on the meter shunt.

Another simplification of this trans-. formation method consists in the application the so-called "economy circuit" or the "partial" transformation, whereby the Measuring transformers are being made smaller and cheaper (so-called divisors). In the present In this case, the voltage (in contrast to the usual use of divisors for lamps) is to be increased. It will be on the simplest part of a single transformer winding caused by the variable resistances reduced 'voltage of z. B. volts (in a 110 volt network) supplied. At the ends of the transformer winding in its entire length then prevails at appropriate choice of the ratios the "desired increased voltage of 110 volts, which is fed to the meter shunt. In this way, the previously discussed advantage is achieved with a single correspondingly subdivided transformer winding. Analog can also be used a multiple transformation both in complete and in economy circuit without Difficulties and in this way also one and the same if necessary self-regulating load resistance for several voltages, e.g. B. in three-wire systems, run simultaneously for 110 and 220 volts.

Claims (2)

Patent Claims: 1. Self-regulating load resistor for current, voltage and power comparison according to D. R. P. 163877, characterized in that with alternating and three-phase current calibrations the meter shunt measuring voltage to be supplied . . by transforming the 'through' prevailing at the constant resistance the variator reduced voltage to a higher resp. appropriate to the meter Calibration voltage is transformed, for the purpose of eliminating any calibration errors caused by non-normal calibration voltages to prevent. 2. Self-regulating load resistance for. Current, voltage and power comparison according to D. R. P. 163877, characterized in that the and three-phase calibration applied transformation of the measuring voltage by means of a so-called economy circuit of the transformer for the purpose of simplifying this measuring transformer is effected.