SU117390A2 - Electrical device for modeling plumbing, ventilation, etc. nets - Google Patents

Description

Basically auth. St. No. 103816 describes an electrical device for modeling water supply, ventilation, etc. networks in which piecewise linear approximation circuits containing series-connected resistances are used as elements reproducing parts of the latter.

The disadvantage of the device described in ed. St. No. 103816, is the power supply of circuits with piecewise linear approximation by alternating current, as a result of which the current-voltage characteristics of these circuits are a function of time. Since, in this case, each element that reproduces a section of a network only works for one half-period of the network that feeds it, it’s very easy to make a model of a real network from these elements to connect them in such a way that while some work, others work It is said that it will cause the wrong decision to be received. Thus, when drawing up a model, it is necessary to observe synchronism in the work of individual elements.

In order to eliminate these drawbacks and increase, therefore, the accuracy of the simulation, as well as to simplify the assembly, a piecewise-linear approximation scheme is proposed to be powered from direct current sources, in particular, from full-wave rectifiers.

To match the electrical resistance of the piecewise-linear approximation schemes with the resistance of the simulated network sections, adjustable resistances are included in these circuits. To reproduce pressure sources with a cost-dependent no. 117390-2 -

Yes, the pressure in series with the indicated circuits includes current sources with continuously variable voltage.

FIG. 1 shows a circuit diagram of an element explaining the operation of the device; FIG. 2 - current-voltage characteristic of this circuit; FIG. 3 - a practical diagram of a simulator; FIG. 4 is a schematic of an apparatus for reproducing pressure sources.

The circuit shown in FIG. 1, consists of several contours. The first circuit contains the resistance R and the VP rectifier, the second - the resistance R, the current source with emf. and straightener VP. The first circuit has clamps for connecting to the network model. When there is no voltage at the input terminals, a current flows through the second circuit.

E 2 D. and in the first circuit there is no current. If the input terminals

apply some voltage U, then a current flows through the first circuit

/ j n, a through the rectifier VP - current / 2 - / i. The volt-ampere characteristic of the circuit (Fig. 2) is represented by a straight line segment. With an increase in voltage U, the current in the rectifier of the VP will decrease to zero, then with a further increase in the input voltage, the current from an external source will flow sequentially along the second and first circuits, and the characteristic equation will now be: and l () - Е ( segment ab in Fig. 2). Thus, the current-voltage characteristic of this device is represented by a broken line, and the number of kinks on the characteristic increases with increasing number of circuits. By changing the resistances R R of the circuits, it is possible to change the angle of inclination of the corresponding segments of the characteristic, and by changing the emf - E „, you can change the position of the break point.

FIG. 3 shows a practical diagram of a four-stage model of aero-hydraulic resistance. It contains: an input rectifier B, assembled according to a bridge circuit and providing the necessary direction of current in the device, regardless of the polarity of the applied voltage; four variable resistances Ri, R, and 4. a four-winding transformer Tr, the primary winding / of which is connected to the AC network, and three secondary //, /// and IV feed the full-wave loop rectifiers that create the required emf . in the circuits and switching rectifiers, the VP automatically turns on the circuits as the current in the device increases. Resistance knobs are supplied with scales calibrated in units of aero or hydraulic resistances.

The same device can be used to reproduce the characteristics of pressure difference sources in networks (fans or pumps). FIG. 4 shows the circuit of such a device, containing; and the rectifier B, the voltage of which can be regulated by means of a special transformer Tp and the automatic resistance of the AC connected in series with it, assembled according to the scheme of FIG. 3. This device allows to reproduce the working areas of the pressure characteristics of all types of turbomachines.

The elements described above allow for any ventilation or plumbing network to assemble its electrical model. Having established the known resistance values on the latter and adjusting the current sources to obtain the characteristics of the corresponding fans B, one can use electrical measuring instruments to study the distribution of currents and voltages in the model, after which, using the accepted modeling scales, find the distribution of costs and pressures in kind.

Claims (3)

1.Electrical device for modeling water supply, ventilation, etc. networks, in which as elements that reproduce parts of the latter, circuits with piecewise-linear approximation are used, containing series-connected resistances according to the authors. St. No. 103816, characterized in that, in order to increase the modeling accuracy and simplify the assembly, these circuits are powered from DC sources, in particular from full-wave rectifiers. 2. The device according to claim 1, characterized in that the piecewise linear approximation circuit includes adjustable resistors, which serve to match the electrical resistance of these circuits with the resistance of the network segments being modeled. 3. In the device according to claim 1, use sequentially with circuits with a linear-linear approximation of the included current sources with continuously variable voltage for reproducing pressure sources with a pressure-dependent pressure. Subject invention Fig 1 Fiyo I & j 4; zbjT fg / 7 fg / 7 f} s) fBn Fig 3