SU414536A1 - SENSOR OF ACTIVE OR REACTIVE COMPONENTS OF SINUSOIDAL CURRENT - Google Patents

Description

one

The invention relates to the field of electrical measuring equipment and is intended to measure the active or reactive components of a sinusoidal current.

A sensor of active or reactive components of a sinusoidal current is known, which contains a current transformer, in the secondary winding of which a rectifier bridge and a load resistor are connected. However, it requires the inclusion of a smoothing filter at the output to smooth out the ripple of the output AC voltage, which significantly reduces the speed of the sensor.

The purpose of the invention is to increase the speed of the sensor. This is achieved by connecting a parallel circuit to the output of the rectifying bridge in parallel with the load, consisting of a series-connected memory capacitor and a key, to the control input of which are connected series-connected blocking generator and selsyn.

FIG. 1 is a diagram of the sensor.

The secondary winding of the current transformer 1 is connected to the input of the rectifying bridge 2, and a load resistor 3 is connected to its output. Parallel to the latter there is a circuit of serially connected storage capacitor 4 and transistor switch 5, the control input of which is connected to the output of the blockg-generator 6. Input the latter is connected to the output of the selsyn 7, operating in transformer mode, and the network voltage is applied to the output of this selsyn.

The voltage drop across the load resistor 3 is proportional at each time point to the absolute value of the load current. The transistor key 5 opens the pulse of the blocking generator 6 and the voltage on the capacitor 4 at the time of the end of the pulse becomes equal to the instantaneous value of the voltage on the resistor 3. This coupling is stored on the capacitor until the beginning of the next pulse. With the help of a selsyn 7, operating in the transformer mode, the pulses of the blocking-heater 6 can be shifted by any angle. If the device is to operate as a reactive current sensor, then the phase of ethnul pulses is set so that the moment of the end of the read pulse corresponds to the transition through the O, for example, P1 of that phase, the reactive component of which is measured. If the device should work as an active current sensor, then the phase of these pulses is shifted by an angle of 90 °. Thus, the output of the device will have a voltage

(Ex 4 COS Wed

for active current sensor

but

 output - 4g sin with - FOR sensor

reactive current; where R is the resistance of the resistor 3.

The maximum possible delay of the sensor is equal to the period of the reading pulses and at a network frequency / s 50 Hz it does not exceed 0.01 sec.

FIG. 2 shows time diagrams for the sensor operation.

L / C is the output voltage of the selsyn,

t / b - output pulses of the blocking generator,

f / 3 is the voltage across the load resistor, t / 4 is the voltage across the storage capacitor.

The time diagrams show the process of changing the load from capacitive to active capacitive if the device operates as an active current sensor. The voltage U is proportional to the active component of the current.

Subject invention

A sensor for active or reactive components of a sinusoidal current, containing

a current transformer, in the secondary winding of which a rectifying bridge is connected and a load resistor, characterized in that, in order to improve the speed, the rectifier bridge is parallel to

a circuit is connected, consisting of a series-connected memory capacitor and a key, to the control input of which are connected a series-connected blocking generator and a selsyn.

S

11c

and

R.