Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
CA 02970403 2017-06-09
Method and apparatus for detecting, evaluating and displaying measure-
ment values of motors of electric drives
The invention relates to a method for detecting, evaluating and displaying
measurement values of motors of electric drives, and to an apparatus for im-
plementing said method.
In numerous technical apparatus, switching operations between mechanical
states are realised by means of electric motors. Frequently, the switching
oper-
ations are cyclic in the sense that always it is switched back and forth
between
at least two defined states. Examples of such electrically driven systems are
barriers for railway transitions, drives for changing the switch position in
rail-
bound traffic, or drives for opening and closing windows, gates, etc. The ser-
vomotors run in a reproducible manner from defined initial points to defined
endpoints and back again.
If the functional capability and the technical condition of such installations
are
to be monitored, it is necessary to make a statement about the sluggishness of
the plant. For this purpose, for example, the electrical characteristic curves
of
the drive motors are determined and evaluated. Sluggishness, which can be
caused by wear, for example, would be noticed by the fact that greater power
consumption of the motor is measured than by reference values.
In order to be able to assess the technical state of an electrically driven
system,
it is a necessary to evaluate the data of measured value.
With respect to switching drives, for example, the current profile during a
switchover operation is recorded and compared with a reference curve.
The data are displayed on an output device with an ordinary coordinate system
in which the measuring time is selected as the abscissa and the current magni-
tude or the difference between the measured current values and the reference
curve is selected as the ordinate.
In such a representation, however, a comparison with earlier or later measure-
ments is difficult to visualise.
DE 197 33 001 Al describes a method for detecting, evaluating and displaying
measured values, in which the measurement or comparison values are dis-
played in alphanumeric form, wherein the alphanumeric representation of a
2
measurement or comparison value is assigned a colour value in the
representation in
each case as a function of the determined comparison value.
The object of the present invention is to provide a method by which the
technical state
.. of motors of electric drives can be assessed not only at a given time, but
also the
transient development of the state is recorded and visualised, so that also
statements
about an expected maintenance scope can be made and conclusions drawn
regarding
the causes of the changes in state. Moreover, an apparatus is to be provided,
which
implements the method.
The method involves a measuring method in which the measured values of motors
of electric
drives are detected, evaluated and displayed. In particular, the electrical
characteristic values
of the motor measured by at least one sensor can be used as measured values.
Moreover,
framework parameters such as temperature, humidity, etc. can also be measured
and
integrated in the evaluation. The measured values are transmitted to a data
processing system
where they are stored and evaluated. In the evaluation, it can be advantageous
to process
appropriately the measured values. For example, an evaluation function can
compare the
measured values with reference values under the specified basic conditions,
and, as further
data to be considered, only use the differences between the measured values
and the
reference values. Since electric motors such as those in the case of drives
for barriers,
switches, windows or gates have a cyclic operating pattern, the measured
values can be
compared with one another as a function of the mechanical position of the
driven components
over a period of several control cycles. For example, if the start-up
characteristic of the motor
changes due to wear-induced sluggishness of the mechanism, the power
consumption
requirement of the drive gradually increases over time. In order to recognise
such a trend at
an early stage, the data have to be compared over a long period. In a display
of the data on a
two-dimensional screen or on a two-dimensional paper printout, a
multidimensional
representation is only clear
Date Recue/Date Received 2022-02-07
CA 02970403 2017-06-09
3
when the information is processed. This takes place according to the
invention,
in that two time coordinates are considered. The measured values within a rev-
olution cycle of the drive are described as a function of one time coordinate,
which is referred to as the rotation time Tu. The second time coordinate is
des-
ignated as the comparison time Tv and it indicates the time of each individual
revolution. Two or more successive revolutions of the drive thus occur at two
or
more different time points Tvi and Tv2 etc. At each of these times, there is a
measured value characteristic during one revolution z = frv,(Tu). In order to
de-
scribe the dependency of the data on both time coordinates, both coordinate
axes according to the invention are selected perpendicularly to one another.
In
x-direction, for example, Tv can be represented, while the y-direction is
charac-
terised by T. Now, on a two-dimensional display plane to be able to display
the
values of the data in the coordinate system belonging to each (yi; zi) pair, a
perspective representation could be selected. However, since this can quickly
become obscure, a projection of the z-axis on the x-y plane according to the
invention is considered. In order to be able to display information about the
nu-
merical values of the data, the zi-values are colour-coded. The sequence of
coloured data points in the y-direction indicates the difference between the
data
value and the reference value within a revolution time Tu, which was measured
at time Tv; during a revolution. During the next revolution of the actuator in
the
same direction, the data values at Tv(j+i) are displayed in the same manner.
Since the (y(i+1); z(i+1)) pairs of values are shifted parallel to the (yi;
zi) pairs
of values in the direction of the Tv-axis, both measurements are shown side by
side and can easily be compared with one another for evaluation. Data values
for the same phases of the changeover operation for different setting
processes
always lie on a parallel to Tv-axis. Thus, the development of the measured val-
ues at each phase of the changeover process can be efficiently evaluated by
analysing the development of the colour along parallels to the x- and/or Tv-
axis.
Particularly advantageously, the information quantity is therefore reduced in
that not every single z-value, but only certain value classes, which are
oriented
towards defined tolerance values for the data, is coded. By comparing the data
with reference values and a specification of one to a few tolerance ranges, a
meaningful representation is achieved with the aid of a few colour values.
Based on the colour of the data point, the tolerance limit exceeded by the
data
point (y; z) is therefore visible.
4
Moreover, it is advantageous if, during the evaluation of the data, attention
is
drawn to the requirement to investigate the drive. This can then occur, for
example, if at least once a data point has reached a tolerance limit to be
defined,
which is known as evidence of damage or hazard to the drive.
.. Moreover, the data points along a parallel to the comparison time axis are
analysed as to whether a change in the data points takes place in the
direction of
a tolerance limit to be defined. Thus, if a data value, at a particular
revolution
phase of the drive, gradually exceeds increasingly higher tolerance
thresholds, it
should be expected that a critical state of the drive is imminent, so that
here a
message is issued at the output unit, which indicates that the system must be
investigated by the service personnel.
According to the invention, an apparatus is provided, which detects, stores,
.. evaluates and displays the measured values of motors of electrical drives.
The apparatus consists of at least one measuring sensor that is connected to a
data processing system, which has an output unit for displaying the evaluation
results as well as means for data input. The measurement data are evaluated by
means of the data processing system.
.. In particular, the electrical characteristic values of the motor measured
by at least
one sensor can be used as measured values. Moreover, the apparatus can also
measure framework parameters such as temperature, humidity, etc., and
incorporate them in the evaluation.
For the evaluation of the data, it can be advantageous if the apparatus
.. appropriately processes the measured values. For example, with the aid of
an
evaluation function, the apparatus can compare the measured values with
reference values under the prevailing framework conditions, and only use the
differences between the measured values and the reference values as data to be
considered further. The apparatus according to the invention considers two
time
.. co-ordinates.
It describes the measured values within a revolution cycle of the drive as a
function of the
revolution time Tu. The second time coordinate is designated as the comparison
time Tv
and it indicates the time of each individual revolution.
Date Recue/Date Received 2022-02-07
CA 02970403 2017-06-09
Two or more successive revolutions of the drive thus occur at two or more dif-
ferent time points Tv, and Tv2 etc. At each of these times, there is a
measured
value characteristic during one revolution z = frvi(ru).
The data are represented in a two-dimensional coordinate system with two co-
5 ordinate axes perpendicular to one another, with Tv as abscissa (x-axis)
and Tu
as ordinate (y-axis).
On its output unit, the apparatus displays the values of the data belonging to
the (yi; zi) pair in the coordinate system by projecting the measured values
onto
the Tu-axis, thereby colour coding the measured values specified by the zi-
values. The sequence of coloured data points in the y-direction indicates the
difference between the data value and the reference value within a revolution
time Tu, which was measured at time Tv; during a revolution. During the next
revolution of the actuator in the same direction, the apparatus displays the
data
values at Tv(I#1) in the same manner. Since the (y(i+1), z (i+1)) pairs of
values
are shifted parallel to the (yi; zi) pairs of values in the direction of the
Tv-axis,
both measurements displayed side by side can be compared easily with one
another for evaluation.
The apparatus advantageously reduces the information quantity by not coding
each individual measured value in the measuring range with its own colour, but
only certain classes of values that conform to defined tolerance values for
the
data. By comparing the data with reference values and a specification from one
to a few tolerance ranges, the apparatus allocates only a few colours to the z-
values. Based on the colour of the data point, the tolerance limit exceeded by
the data point (y; z) is therefore visible.
During the evaluation of the data, the apparatus advantageously indicates an
investigation requirement of the drive. This can then occur, for example, if
at
least once a data point has reached a tolerance limit to be defined, which is
known as evidence of damage or hazard to the drive.
Moreover, the apparatus analyses the data points along a parallel to the com-
parison time axis as to whether a change in the data points takes place in the
direction of a tolerance limit to be defined. If a data value at a particular
revolu-
tion phase of the drive gradually exceeds higher tolerance thresholds, the
appa-
ratus issues a message at the output unit, which indicates that the system
must
be investigated by the service personnel.
CA 02970403 2017-06-09
= 6
The invention is explained below in more detail with reference to an exemplary
embodiment that is represented by two figures.
Fig. 1 shows, by way of example, the analysis of switches on a railway network
of a track-bound traffic system. By means of magnetic field sensors that are
designed, for example, as 3D or multi-dimensional magnetic field sensors, the
current magnitude and the direction of rotation of the switch drive are deter-
mined by means of the measured magnetic fields by a data processing system.
The current curve is used in the analysis of the data as a measure of the slug-
gishness of the switch.
In the figure, a single dash is assigned to each 4-wire switch drive cable; 3
switches are thus monitored with the diagnostic apparatus.
The diagnostic apparatus directly measures existing cabling of the respective
switch drive, near a clamping strip. The clamping strip between the outer
cable
and the inner cable is ideal for this purpose.
The measurement data is transmitted by means of a suitable interface. In this
example, a 4-20 mA interface is used. Depending on environmental conditions
and distances, also, other wire-bound interfaces are possible, as well as wire-
less, e.g. radio interfaces.
The control of the measuring process, the preparation of the measured data
and the forwarding to a diagnostic system are functions of the connected data
processing system.
Fig. 2 shows an exemplary representation of the switch-drive measurement da-
ta. The measured current values are subtracted from the reference values of an
intact drive stored in a database.
The differences from the reference values, Al, are divided into tolerance rang-
es. In this example, none or only slight deviations from the reference value
are
assigned to the tolerance range TO. Greater deviations correspond to tolerance
ranges T1 to T4. When the tolerance range T4 is reached, an acute danger to
the operability of the drive exists.
Negative deviations feature a better sluggishness of the drive in comparison
to
the reference values. These measured values are assigned to tolerance range
CA 02970403 2017-06-09
7
T-1. Each tolerance range is now assigned its own colour when displaying the
measured values.
In this example, the colour green is assigned to the tolerance range TO and
thus a match between the measured data and the reference values or it is only
.. a minor deviation. Ti to T4, for example, the colours yellow, orange, light
red
and are assigned dark red, T-1 the colour blue.
The comparison time Tv plotted in the x-direction, the y-direction shows the
measured values during a revolution (Tu) of the drive. The movement of the
switch drive into a right-hand position is shown, starting from the x- axis,
in the
middle of the figure, while the data shown from the centre upwards describe a
deflection of the drive into the left position. Along the Tv axis, several
revolu-
tions are displayed side by side. The switch drive comes to the end position
after about the same period of revolution TUE. The same phases of the revolu-
.. tion are therefore comparable along the parallels to the Tv-axis.
In the lower section of Figure 2 (clockwise), it can be seen how the values
gradually deviate from the reference value over several revolutions during ap-
proximately half the period of revolution. This can be seen in the fact that
in the
case of Tu, the colour has migrated from green to yellow over orange in the
.. range of half revolution cycle time along a parallel to the Tv-axis. For
the first
revolutions at the beginning of measurements, the measured value still corre-
sponded with the reference value, whereas the number of revolutions was more
and more distant from its reference value.
This is an indication that the condition of the drive has deteriorated as corn-
pared to the start of the measurements, and thus, there is a need for mainte-
nance before the drive reaches a critical state. When analysing the data, an
order to inspect the switch is triggered. In this case, a prediction of
expected
damage history is displayed by comparison with data stored in the database.
Based on this forecast, the optimum maintenance time can be defined.
.. In the upper area of Figure 2 (anti-clockwise), it can be seen, for
example, how
a sudden transition from green colour values to red takes place. An event has
occurred here and damaged the switch, which must be corrected immediately.
Correspondingly, an alarm message is issued and an immediate check of the
system is triggered. The spare parts required for repair are determined and
dis-
played from comparison with the data stored in a database.
