SU1251046A1 - Protection unit - Google Patents

Abstract

This invention relates to stabilized power supplies with protection. The aim of the invention is to simplify and increase the reliability of the protection unit. The goal is achieved by those. that in the event of an overcurrent on the current sensor 12, the voltage increases and a positive voltage appears at the output of the differential amplifier 3. Transistor 4 opens, transistor 7 closes. Load de-energized. The diode 13 and the capacitor 14 support the formation mode at the output of the amplifier 3 positively. voltage and after the disappearance of the overload despite the fact that the voltage on the sensor 12 has decreased. A reset is made by closing the contact. 1 il. with SS h-J to SP 77 4; about

Description

The device relates to electrical engineering, in particular, to protection devices of primary and secondary sources, and can be used as an independent one in the protection of primary sources, as part of secondary power sources.

The purpose of the invention is to simplify and increase reliability.

 The drawing shows a schematic diagram of the protection unit.

Parallel to the input buses of the device + and - the param- eter stabilizer of resistor i and zener diode 2 is connected. The output of the stabilizer is connected to the power supply buses of the differential amplifier 3, and the output of the latter is connected to the input of the executive node through the base of transistor 4 through the resistor 5 and the zener diode 6. Transistor collector connected to the control input of the switching element on the transistor 7 (it can also be a regulator regulator transistor). The inputs of the differential amplifier are connected to a current-to-voltage converter on the basis of a measuring bridge filled with resistors 8-11, the single arms of the arms of this bridge are connected to a current sensor 12 connected to the common bus, the second terminals are connected to the output of a parametric stabilizer diode 13 is connected to the output + th --.- and the second to the common input terminal through the capacitor 14 and through the parallel-connected capacitor in open contact 15 Resistor 16 is connected in series with the diode 13 (shown th). Output terminals of the device are connected to the load circuit 17 "

The device operates as follows.

When power is applied to the input terminals + and - in the load circuit 17: the operating current flows if it does not have an overcurrent. At the output of the parametric stabilizer (Zener diode 2) a stable voltage is generated, which is the supply voltage for the differential amplifier 3 and the measuring voltage. bridge resistors 8-11 last selected in such a way that the inverting first input of the amplifier 3 voltage in the initial mode

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ment and at a later time higher than the second non-inverting input.

The output of the amplifier in this case will be zero voltage, and the transistor 4 is closed and the transistor 7 is open. The capacitor 14 provides an initial voltage imbalance if the output voltage of the device lags slightly in phase from the supply voltage of the measuring bridge.

When an overcurrent occurs on the current sensor 12, the voltage increases and the differential amplifier overturns because the output + voltage is greater than the input -, and a positive voltage appears at its output, which creates a current in the base of transistor 4 and the latter opens, while the transistor 7 is closed. The diode 13, which is prior to the appearance of an overload displaced in the opposite direction, shunts the half-arm out. resistor 10, reducing even more the voltage on the inverting input of the amplifier 3, keeping it in the position when a positive voltage is formed at its output. This is also provided by the capacitor 14, which maintains the initial voltage level at the input 1 of the differential amplifier after a failure of the overload signal from the current sensor J2. Thus, despite the fact that the voltage on the current sensor 12 has decreased, since the load has de-energized.) Ushshtel 3 does not change its state. When contact 15 is closed, the amplifier returns to its original state when transistor 4 is closed and transistor 7 is open.

The load of amplifier 3 can be a relay coil, the closure of the contact which provides current to the load circuit 17, and when this relay is turned on - the de-energization of this circuit,. when overloaded

The power node can also be implemented in such a way, when the transistor 4 controls the relay, the break contact of which provides the switching of the load circuit 7 to the power source. The zener diode 6 serves to lock the transistor 4, the resistor 16 is set, if the load is low-resistance or capacitive, to provide the initial state for the circuit, since the output voltage may lag behind the input when it is fed to the inputs. Pin 15 is set to ensure that the protection unit returns to its original state without disconnecting from the input buses.

Claims (1)

Claims of the protection unit comprising an actuating node whose switching element is included in the power bus, a differential amplifier whose input is connected to the output of the current-to-voltage converter, and an input of the actuating node, a parametric stabilizer, one input of which is connected to the output switching element and diode 1251046 with in order to simplify and increase reliability, a capacitor is connected to it, connected between the common bus input input and the first input of a differential amplifier, the second input output of which is connected to the output of the switching element of the actuating unit through a diode, and the current converter voltage is made in the form of a current sensor included in the common bus and a measuring bridge, one diagonal of which is connected to the output of a parametric stabilizer, another input which is connected to the common bus input input, and the other bridge diagonal is the output of the current to voltage converter.