SU1555850A1 - Device for sensor switching-on of thyratron - Google Patents

Abstract

The invention relates to a pulse technique and can be used in input and output devices. The aim of the invention is to increase the operator's electrical safety by reducing the current through it, achieved by introducing isolating transformer 8 and capacitor 9. The device contains a thyratron 1, resistors 2 and 3, a storage capacitor 4, a rectifying diode 5, phase bus 6 , a common bus 7, a decoupling transformer 8 and a capacitor 9, whose capacitance is C _Z Σ * 9810 C _Z , where C _Z is the capacity of the operator’s body relative to the ground. 1 il.

Description

(L

with

cn cd ate

00 SP

The invention relates to a pulse technique and can be used in input and output devices. The purpose of the invention is to increase electrical safety by reducing the electric current flowing through the operator, achieved by introducing an isolation transformer and an additional capacitor.

The drawing shows an electrical functional circuit diagram of the device.

The device for the switching on of thyratrons contains a thyratron 1, the first and second resistors 2 and 3, respectively, forming the anode and cathode circuits of the thyratron 1, a storage capacitor C, a rectifying diode 5, a half-wave rectifier, a phase wire 6 of the AC network and neutral wire 7, isolation transformer 8 and additional capacitor 9.

The device works as follows.

Before touching the grid output of a thyratron 1, the voltage on it is not enough to cause a discharge, therefore, the thyratron 1 is locked. When a finger touches the grid outlet, the device introduces its own body capacity relative to the ground. An alternating current circuit arises: the phase conductor 6 of the alternating current network — capacitor 9 — anode to the thyratron circuit (second resistor 3) —the capacitance of the anode-grid gap of the thyratron — human capacitance C and ground. As a result, an alternating voltage is induced on the grid of the thyratron 1 with a network frequency, under the action of which an anode-grid and a cathode-grid breakdown occurs. A pulsating preparatory discharge current arises in the grid circuit, which provides ignition preparation for the main gap anode-cathode. Thyratron 1 goes into the Enabled state. When the grid of the thyratron 1 and any grounding object is simultaneously touched, there is no increased danger situation in this circuit, since the source of constant voltage of the power supply to the tirathron T does not have a galvanic connection with the ground This current, due to the high grid potential, does not flow through the human body. Alternating current,

0

caused by high mains voltage, limited by the complex resistance of the phase-to-person circuit and, first of all, by the capacitance of the additional capacitor 9'1

from 75s

where 00 is the mains voltage frequency; C - capacitor capacitance 9.

In order to preserve the sensory sensitivity of the thyratron 1 in this scheme, it is necessary to fulfill the condition where Cr is the capacity of the operator’s body relative to the ground. In this case, the level Uc of the voltage induced on the grid of the thyratron 1 is determined by the expression (1) С,

in

8N eKV.

 CB "eq

(one)

five

50 55

thirty

35

40

45

where Svh is the input capacitance of the thyratron 1, determined by the capacitance of the gap, the anode grid, taking into account the mounting capacity

g C Cr

NN eq -

Considering that a typical value of a person’s own capacitance of about 70 pF, the effective value of the short-circuit current flowing through the human body in the proposed device is in this case a negligible value (units of microamps)

The second condition, C i10Cz, is necessary to maintain high electrical safety, since with a tenfold increase in the capacitance of capacitor 9 relative to capacitance C, the short-circuit current reaches several tens of microamps.

Claims (1)

Invention Formula A device for sensory switching on thyratrons, containing a sensor pad, a glow discharge thyratron, phase bus, common bus, first and second resistors, a rectifying diode and a storage capacitor, the first terminal of which is connected to the rectifying diode anode and through the first resistor to the cathode glow discharge thyratron, characterized in that, in order to increase the electrical and safety of the operator, an isolation transformer and an additional capacitor connected between the phase terminals of the primary 5 15558506 and the secondary windings of the disconnecting discharge, the grid of which is a transformer, the primary winding is connected to the touch pad, the cathode is connected to the phase output of the pickup diode and connected to the phase bus of the network, and the second output to the second output of the transient common transducer bus, phase output of the secondary transformer, with the additional capacitance C connected to the second output capacitor constituting the storage capacitor and through the Cg. C - JUS Ј where Cz is the body capacity of the second resistor - to the anode of the thyratron operator relative to the common bus.