SU1748078A1 - Meter of reactive and active components of electric current - Google Patents

Abstract

Usage: electrical meters in the metering and control of electricity consumption. The essence of the invention: the meter contains a voltage transformer 1 connected by its inputs to the busbar section 2 of the third phase C, and the outputs to the controlled current generator 3, the outputs of which are connected to the terminals of the measuring capacitor 4 and to the inputs of the analog-digital converter 5, input control generator 3 is connected to the outputs of the Comparators 6,7 and with the counting input of the counter 8 positional code, one of the outputs of which is connected to the input of the analog-digital converter 5, the second output to the reset input of the controlled g generator 3, the inverting input of the comparator 7 is connected to the neutral wire, non-inverting - to the second phase wire B, the inputs of the comparator are connected to the first phase wire A and to the neutral wire through switch 9. 2 Il.

Description

where IK is the amplitude of the total current of the K-th harmonic;

where Ki is the voltage transformation ratio:

K2 is the voltage-to-current conversion factor;

lc (t) is the phase C current;

g - resistance section of the busbar 2.

Consequently, at the output of the controlled current generator 3, a current is generated that is proportional to the measured

1 kYM Ki K2T lc (t).

(7)

At times when positive pulses from comparators 6 and 7 arrive at the resolution input of the controlled current generator 3, the output current 1out (1) goes to the capacitor 4 and charges it (fig. 2z). If there is no voltage at the input of the generator of current 3, the output current 1 output (1) is zero and the voltage on the capacitor 4 remains unchanged, i.e. remembered. When the next resolution pulse goes on, everything happens in the same way. Thus, after several resolution pulses, charge accumulates on the capacitor 4 (FIG. 2, c). Voltage is equal to it

 5 pDML tfj I

(eight)

where Ko Kg K2 t.

Thus, taking into account formulas (2) - (5), the voltage on the capacitor 4 is equal to the sum of the amplitudes of the reactive or active current harmonics (depending on the position of the switch 9).

Next, the last pulse in the series of voltage accumulation pulses on the capacitor 4 records this voltage in the analog-to-digital converter 5, at the output of which output information is generated about the level of this voltage and, therefore, about the magnitude of the active or reactive currents

The next pulse from comparators 6 and 7 through the counter 8 of the position code discharges the capacitor 4 to zero and the whole measurement cycle starts again (Figure 2h, and),

The advantages of the proposed meter are a more accurate measurement of the components of the electric current and the reduced effect of current surges occurring at the moments of switching and when the technological equipment operates on the magnitude of the measured current, due to analog integration over several periods,

Claims (1)

which allows you to more accurately take into account the energy consumption at the enterprise. The invention of the meter reactive or active the components of the electric current, which contains the measuring capacitor, the switch Y el, connected between the first phase wire of the monitored network and the neutral wire, characterized in that that, in order to improve the accuracy of measuring the reactive or active components of the electric current in the region of low current values and with non-sinusoidal current form and increase noise immunity, two comparators were additionally introduced in it, a position code counter, an analog-digital converter, a controlled current generator and a transformer tensions, with the first fixed the contact of the first contact group of the switch is connected to the neutral wire and the second moving contact of the second contact group of the switch, the second fixed contact of the first contact the switch group is connected to the first phase wire and to the first fixed contact of the second contact group of the switch; the moving contact of the first contact group of the switch is connected to the inverting input of the first comparator, and the moving contact of the second contact group of the switch is connected to the non-inverting input of the first comparator, the inverting input of the second comparator is connected to the neutral wire, and the non-inverting input of the comparator is connected to the second phase wire, the outputs of the comparator are connected to the counting input of the position code counter and enable the controlled current generator, one output of the position code counter is connected to the control input of the analog-digital converter, and the other output of the position code counter is connected to the reset input of the controlled current generator, the outputs of which are respectively connected to the inputs of the analog-digital converter connected in parallel measuring capacitor, controlled inputs 0, the current generator is connected to the first and second terminals of the secondary winding of the voltage transformer, the first and second terminals of the primary winding of which are connected to the third phase wire. five f "/ UP P" L LQPPt mpp. pgl Gs lkg 1s relock four LKT "And LY4H "Y / y / V v v LQPPt1 "A / gL W R if