DE241431C - - Google Patents

Description

IMPERIAL

PATENT OFFICE.

PATENT LETTERING

- M 241431 CLASS 21 c. GROUP .57.

Identification device for automatic current limiters.

Patented in the German Empire on March 19, 1911.

In the case of electrical systems with calculation according to the flat rate, in many cases automatic current limiters switched on, which when the stiom limit is exceeded through periodic lighting and extinguishing of the lamps the consumer draw attention to the inadmissible removal. Since the periodic decrease and increase makes the light unsuitable for the consumer, the consumer himself has an interest to go below the established limit again. But now it happens often suggest that by switching on many lamps the current limit is reduced by a significant one Piece is exceeded, the state is sometimes also out of willfulness or carelessness of lighting up and going out for a long time, and even will after crossing the border on purpose

so still lights turned on. All of these accidentally or intentionally induced large currents, the small and therefore easily damage or at least damage sensitive automatic current limiter change their set calibration value, and it is not necessary to prove to the consumer afterwards that that only the overcurrent brought about by his fault is the cause of the Damage is. In order to provide this proof, the following procedure can be used serve new facility.

In the schematic figure, s means the current limiter, which is used here as a simple one Electromagnet with spring loaded armature

is indicated and which opens a contact in the event of an overcurrent. The electromagnet is now preceded by a resistor w , which results in a small voltage drop in the current, for example _1? 0.5 volts. A very fine wire k is connected in parallel to this resistor w , the state of which is an indicator of the previous use of the apparatus.

As assumed, the characteristic wire k is very fine in relation to the resistance w and has a comparatively very small mass, so its temperature follows the current fluctuations very quickly. The much stronger and more massive resistance w , on the other hand, heats up more slowly and also cools down more slowly. As a result of this thermal inertia, it is to a certain extent only loaded with the mean current and by far does not reach the temperature that corresponds to the respective maximum value of the periodic current. The period of the current can be assumed to be one or more seconds. The temperatures of the identification wire, on the other hand, go through values which almost always correspond to the maximum of the periodic current. While the resistance w remains practically unchanged in the event of an overcurrent with the correct choice of the ratios, the identification wire melts through or at least later shows unmistakable signs of a higher temperature suffered. The melting of the fine identification wire has practically no effect on the play of the apparatus, which should not be interrupted so that the consumer is not completely cut off

and can go back to the permissible amperage.

However, with the device described, it is possible to prove to the consumer without a doubt that the intentional or unintentional strong overcurrent caused by him is the cause of possible damage to the apparatus has been.

Instead of a special resistor w ίο, the identification wire can also be connected in parallel to the electromagnet of the current limiter or to any part of the circuit with a relatively high thermal inertia.

Claims (1)

Patent Claim:. Identification device for automatic current limiters that detect the exceeding of a indicate the set limit by periodically increasing and decreasing the current, characterized by a fine Tracer, which is part of the circuit with relatively high thermal inertia is connected in parallel, for the purpose of the condition of the tracer to be able to conclude on the previous improper use of the current limiter. For this purpose ι sheet of drawings.