SU396783A1 - DEVICE FOR CONTROL OF CURRENT AVAILABILITY - Google Patents

Description

one

The invention relates to devices for protecting and controlling the power circuits of a multi-phase device, whose switching is controlled by a relay, for example, by controlling the temperature of a furnace In automatic systems using Latitude-Modulation modulation. In these systems, either mechanical co-ordinates, actuators, magnetic amplifiers in relay mode, or contactless thyristor switches are used as starters.

A device is known for "the presence of voltage on a multiphase load.

The described device, the control of the al-icy of the current in the phases of multi-phase load, has a greater sensitivity | the fact that a relay converter of the period between pulses into an analog signal is used as the executive body, whose output is connected to the control input of the thyristor or ale: CTRO | Mechanical contactor and through a resistor with an operational source of voltage, and the input through the logical element "OR with current sensors.

A schematic diagram of the proposed device is shown in the drawing.

A device for monitoring the current in the phases of a multi-phase load contains a source of a multi-phase mains voltage, contactor 2, sensors: ka 3, which form an impulse

for half the period of alternating current in phases 4 of a multiphase load 5, for example, made from a ferrite core with one winding; the logical element OR 6, the relay converter of the period between pulses into the analog signal 7, the operational voltage source 8, the resistor 9 and the alarm indicator 10. In the initial state, the output of the operational power source is high. and potential; alternating voltage from source / through. Stacker 2 is applied to load 5; 11 pulse 1 from the output of the dacha pc, PMPploud. which are proportional to the flow through the multi-phase load 5, the signal is transmitted to the logic element OR 6. The pulse frequency from the output 12 of the logic element 6 is by the number of load phases greater than the frequency of the network. The resistance between the output 13 of the relay converter 7 and the common wire is high, and the entire current source 8 through the resistor 9 is fed to the control input of the contactor 2, keeping it in the on state. In svn

with a small voltage drop across the resistor 5, the alarm indicator 10 indicates that there is no alarm.

Iri iroiadiln current at least in one phase 4 from the output of the corresponding current sensor

3, the PULSES disappear and, as a result of the logo, the time between the pulses at the output of logic element 6 increases, and this is a signal for the relay converter for the period between pulses to MIS to change its steady state. The output resistance between the output 13 and the common wire becomes izkim, and all the current from the operational source 8 begins to flow through the output 13. This leads to the fact that the contactor 2 de-energizes the load 5 and is disconnected from the source. At the same time, in connection with the increase in the voltage of the ipesHCTOpe 9, the alarm indicator 10 gives information about the accident.

Since only the period between the pulses from the logical element OR 6 is used as the information about the accident, the sensitivity offered in the proposed device is much higher than in the known device.

If necessary, this sensitivity can be lowered due to the inclusion of a threshold element in front of the converter 7, which transmits only those pulses to the input of this converter whose amplitude is greater than a specified value. At the same time, functional capabilities of the proposed device are expanded (for example, using the device it is possible 1 to check the violation of the stress measurement).

After elimination of the malfunction, it is necessary to briefly remove the supply voltage from the terminal 14 of the converter 7 to reset the device to the initial state. This can be done automatically if you use the output from the output source of the operating source as the voltage. This output from output II operational source 8 contactor 2 is open. The fall of the voltage on the resistor 9 is zero, and sigalizator 10 indicates the norm when no output

Impulses With Sensors 3.

After the occurrence of a high potential at the output of the olerative source S, the converter 7 will go into a state corresponding to an alarm if after a predetermined time at the input of the converter 7 (output of element 6) a signal appears.

PRED ME of the invention

A device for monitoring the presence of current in the phases of a Multiphase load, containing a contactor, an operational voltage source, sensors, ka, included in all phases of the load, the outputs of which are connected to the inputs of the logical OR element and the actuator In order to increase sensitivity and speed, a perimeter relay converter is applied as an actuator between the pulse W to analog signal, the input of which is connected to the output of the logical element "OR, and the output to the input of the control element ontactor and through a resistor with onepaTHiBHbiM voltage source.