Brush fire meter
A brush fire meter is an electronic measuring device for evaluating the brush fire of commutator machines during testing, monitoring, manufacturing and operation. This makes it possible to make an objective assessment of the brush fire intensity. This is important because a stronger brush fire leads to increased wear and tear and thus to higher maintenance costs and interfering signals for radio receivers (e.g. radio, television) can arise.
functionality
There are basically two options for measuring brush fire. Either the voltage fluctuations at the electrical source can be measured (in the form of armature feedback ), or the acoustic or visual effects of the brush fire can be recorded and assessed.
Measure the voltage fluctuation
One possibility is the acquisition and evaluation of the disturbance voltage curve of the armature voltage. Positive and negative impulses are evaluated separately by a two-channel setup of a measuring circuit, whereby both channels are electronically interlocked. The disadvantage of this method is that, on the one hand, the selection criteria must be coordinated depending on the type of commutator machine and, on the other hand, the selection of the components of the interference level assigned to the brush fire is not always unambiguous, since the back flanks of the pulses for triggering the can lead in its priority opposite channel.
An improvement of this process was presented on September 6, 1988 by Ulrich Münch, Eberhart Paulig and Uwe Gensch. The circuit has been improved in that a signal corresponding to the interference voltage level of the commutator machine is applied to a minimum amplitude detector and via a level regulator to an edge steepness detector, the outputs of the detectors are AND-linked to the inputs of a flip-flop circuit, the evaluation and display means are connected downstream and that a pulse duration signal detector is also connected between the level regulator and the flip-flop circuit, the other output of the flip-flop circuit being fed back to the pulse duration signal detector via a delay circuit.
Measure the side effects
Another method is to evaluate the high frequency electromagnetic noise of the brush fire, submitted by Tanisaka Satoshi, Michiguchi Yoshihiro and Satau Tsuguya on August 20, 1983. Both the electromagnetic and the high-frequency acoustic waves are compared with one another to enable an assessment of the brush fire. A total of six local and external antennas are provided for this purpose, which separate internal and external signals in order to enable optimal measurement. A precise measurement is made possible by the fact that the propagation speeds of the individual waves on the surfaces of the given machine parts are taken into account, so that the measuring device must be adjusted to the respective machine type.
supporting documents
- ↑ Eberhart Paulig, Uwe Gensch, Ulrich Münch: Circuit arrangement for evaluating the brush fire of commutator machines . Ed .: Technical University of Dresden.
- ↑ Yoshihiro Michiguchi, Tsuguya Sato, Satoshi Tanisaka: Spark monitoring device of current collection part of rotary electric equipment . Ed .: Hitachi Ltd.