There are people whose state of health requires permanent supervision. There are a number of medical or aging-related conditions that can have quite an impact on the daily life of these people, therefore, in order to provide them with proper assistance and care, various health monitoring devices have been developed. This article proposes the use of advanced technologies with the help of which we can observe and record the changes in the position of a person with such problems. The equipment has a sensor that can determine the position of the body by measuring the height from the ground. The device can be integrated into a belt or bracelet to record data in real time. This data is analyzed and interpreted by means of a program. The program can detect changes in posture, providing notifications and alerts when the person has suffered a fall. Greatly simplifying surveillance, the device also provides an objective assessment of a person’s balance ability. Since each person has a specific posture and movement, the developed device must be tested and adapted to adjust the coefficients in the program, to avoid the triggering of false events.

To create high-performance equipment, low-performance components, such as those from the old generations, can also be used. For example, if a conditioning stage (amplification/attenuation or filtering) is made with high-end components having increased performance, the costs are appropriate – using “classical” functional ones, the price of the equipment will become competitive. Low-cost devices may have features that do not make them attractive for inclusion in high-performance equipment but certain errors’ analysis may lead to practical and useful results. A converter circuit from PWM pulses to DC voltage was used. Experimental determinations were made using several types of operational amplifiers and errors analysis and correction was carrying out.

In this work, some analytical formulas based on experimental tests are presented that can be used to estimate the heating of the crimped connections used in construction of electrical machines, saving the experimenter from additional, long and expensive tests. The formulas are based on the energy balance equation and combine practical results obtained from previous steady-state heating cycles for a set of 6 crimped connections of the same type, at currents close to the nominal value. There are standards that allow the estimation of the heating of the elements in the circuit at small variations of the test current. Thus, based on the heating obtained at one value of the current, the heating at another, slightly different value can be estimated, without the need for the actual experiment. For a more accurate estimation, the variation with temperature of the electrical resistances of the 6 connectors must be taken into account, which allows the extension of the estimation range. In this case, if there are two heating cycles performed at two different values of the current, estimations can also be made at other values, much different from the two. A global temperature coefficient of resistance can be deduced that can simplify the formulas while keeping the precision, serving to estimate the average heating of the connectors. The formulas have been validated for several types of crimped connections used in the construction of electrical machines.

The paper presents the mathematical support and the results of some simulations related to a new method of analyzing the stability of induction motors powered at variable frequency. After a brief introduction to the proposed issue, the mathematical model of the motor, written with relative values, is detailed. Taking this model as a starting point, a Matlab stability analysis program was created. By running this program, a series of graphs were obtained, detailed in the paper (two graphs are represented each, obtained for different conditions, which facilitate their comparison and obtaining conclusions). They refer to four specific cases regarding the modification of static inductance, rotor inductance, stator resistance and rotor resistance. Analyzing these graphs, the necessary conclusions were drawn. The conclusions are important, mainly in the design phase of the machine, to finalize the structure corresponding to the most stable operation of the drive system with asynchronous motor and static voltage and frequency converter. They highlight the influences of the most important parameters of the motor on the stability of the functioning of systems with such a structure. The paper ends with a representative bibliography for the proposed study.