SU537425A1 - Device for changing frequency at a given speed - Google Patents

Description

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The invention relates to devices for relay protection and automation of energy systems, in particular, to devices for setting and checking the settings of the operation of the frequency change speed relay, the time of the frequency relay actuation.

The closest technical solution to the invention is a device for varying the frequency at a given speed, comprising a series-connected reference frequency generator, a trigger frequency divider, differentiating circuits and a power amplifier 1.

Such devices do not allow the frequency to vary at a given speed.

The aim of the invention is to increase the accuracy of the device. The goal is achieved by introducing a pulse counter, a matching circuit and an OR circuit, the pulse counter inputs are connected to the output of a frequency divider, the outputs of pulse counters are connected through the first inputs of a coincidence circuit to the trigger inputs of the frequency splitter, which set the triggers to one, and the outputs of the differentiating circuits are connected via the OR circuit to the second inputs of the coincidence circuits.

The drawing shows a block diagram of the proposed device for changing the frequency at a given speed. The device consists of a reference frequency generator 1, trigger frequency divider 2, power amplifier 3, output transformer 4, differentiating circuits 5, OR circuit 6, coincidence circuit 7, pulse counter 8, switches 9, 10 frequency divider trigger triggers.

From the crystal oscillator 1 to the input of the frequency divider 2 receives the pulses of the reference frequency. Voltage from the direct and inverse outputs of the last trigger of the divider

frequencies are fed to the differentiating circuits 5. At the same time, the voltage from the direct output of the last trigger of frequency divider 2 goes to the power amplifier 3 and the output transformer 4, the output of which

receive a sinusoidal voltage of alternating current. To change the frequency with a given speed, the direct output of the last trigger of frequency divider 2 is connected to the input of pulse counter 8. The output signals of the trigger of counter 8 are fed to the first inputs of the matching circuits 7, to the second inputs of the matching circuits through the circuit OR 6 the output pulses of differentiating

The circuits corresponding to the leading and falling edges of the output voltage of frequency divider 2. If two units coincide at the input of circuits 7, from their output the frequency divider 2 triggers the signal to set them to the state "1.

In this way, the summation or subtraction of a given number of pulses in a binary positional code is carried out.

So, if in the first period the counter 8 will be set twice to the state "1 first bit of the frequency divider, then in the second period - twice it will be set to" 1 second bit of the frequency divider, etc. Therefore, the duration of each period will change at a given speed. A change in speed by 2 times is possible by connecting switch 9 of the input of counter 8 to the direct output of the penultimate trigger of frequency divider 2, etc.

A change in speed of 1.5-2.5 times is carried out by switching the switch 10 of the differentiating circuit from the inverse output of the last trigger of the frequency divider to the inverted outputs of the previous triggers of the frequency divider.

The use of the proposed device for setting the frequency change rate allows to obtain a stable value of the rate of change of the period duration in the entire frequency range. In contrast to the known schemes, the proposed device provides a frequency cycling at a given speed from the value of fmm to / max after each filling of the counter 8.

Claims (1)

1. R.S. Ermolov. Digital frequency meters. “Energie, L., 1973, pp. 18-36 (prototype).