SU1354323A1 - No-voltage alarm - Google Patents

Abstract

The invention relates to electrical engineering. The purpose of the invention is to reduce power consumption by selecting the value of a resistor connected in parallel with the power source. In this case, the value of the resistor is selected from the condition of providing the open transistor mode for the required response time. 1 il.

Description

The invention relates to devices for monitoring and detecting the disappearance of voltage and can be used in automation systems.

The purpose of the invention is to reduce energy consumption.

The drawing shows a voltage failure detector circuit.

The voltage disappear detector contains a power source 1, the negative terminal of which is connected to the cathode of diode 2, resistor 3 and the base of transistor 4, the emitter of which is connected to the anode of diode 2 and the negative plate of capacitor 5, the positive plate of which is connected to resistor 3, resistor 6 and winding electromagnetic relay 7, which is connected to the collector of transistor 4. The positive terminal of power supply 1 is connected to resistor 6. Diode 2 is bridged by a capacitor 8, Closing contacts 9 of electromagnetic relay with idetelstvuet disappearance of voltage on the power supply terminal 1.

The voltage disappear detector works as follows.

In the initial de-energized state of the circuit of the detector, the contacts 9 of the electromagnetic relay are open. When powering the circuit from source 1 pi. This starts the charge of the capacitor 5 through the resistor 6 and opens the diode 2, the voltage applied to which is applied the opposite polarity between the emitter and the emitter of the transistor 4, while the transistor 4 is closed and the electromagnet relay does not operate. At the end of the charge of the capacitor 5, the current through the diode 2 decreases to the magnitude of the leakage current of the capacitor, and the voltage between the base and the emitter of transistor 4 is close to zero and the transistor maintains its closed state for the entire time of control. At the time of the loss of the supply voltage at the terminals of the source 1, the voltage of the charged capacitor 5 is applied positively. through the resistor 3 to the base of transistor 4 and the cathode of diode 2, and minus to the emitter of the transistor and the anode of the diode, while diode 2 closes and transistor 4 opens, the electromagnetic relay trips to the time when the capacitor discharges 5 to release the relay. The contacts 9 of the electromagnetic relay are closed, which indicates the interruption of the supply voltage. After the capacitor 5 is discharged, pins 9 are opened and the circuit returns to its original state.

Thus, the energy consumption of the detector in the monitoring mode is determined by the value of the resistor 3,

connected in parallel with power supply 1. In this case, the value is selected from the condition of providing the open transistor mode for the required time of operation of the relay

and

-my

iR 6 | 3g.

where R is ve: the cause of the resistor 3;

Uj. - voltage of the charged capacitor 5, - I - maximum allowed current

base transistor - p - gain base

current transistor;

g is the resistance value of the winding of the electromagnetic relay. The value of the capacitor 5 is chosen, based on the required response time of the electromagnetic relay using the formula

WITH

where C is the capacitance of the capacitor 5;

and - the voltage between the collector to

and the emitter of the open transistor;

Up is the release voltage of the electromagnetic relay;

tu is the required response time of the electromagnetic relay. The capacitor 8 by its shunting action protects the transistor from possible interference induced in the power supply circuit of the detector and, in addition,

can select short-term power supply voltage drops, thus providing increased noise immunity.

Claims (1)

Invention Formula The voltage disappear detector contains the capacitor connected by the first pin, the coil of the electromagnetic relay and the resistor, the second diode of which is intended to be connected to the negative pole of the power source, and I also distinguish the diode and the transistor 5 31354323 Sch and with the fact that, in order to reduce the horn is connected to the emitter of the power transistor, the collector of the transit and the second terminal of the capacitor, and the transmitter is connected to the second terminal, the output terminal of the capacitor is connected to the coil of the electromagnetic relay, which is introduced by the second resistor, another It has a terminal for connecting to the negative terminal of which is intended for the positive pole of the power source, and switching to the positive pole is connected to the cathode of the diode, the anode of the power source.