FR2791190A1 - Monitoring of protective conductors in an electrical installation, particularly earth connections in industrial installations - Google Patents

Abstract

The earth continuity monitor has a terminal (1) connected to the earth conductor (9) and another terminal (2) connected by another conductor (11) to a sensor (10). A low voltage source is used to inject a current into the earth conductor, and this current is monitored by the sensor to detect a break in earth continuity.

Description

The present invention relates to a device for continuously monitoring

the

  connections of the protective conductor called "earth" from a given point to another.

  This device will find its application in the field of installations

  electrical and especially in the industrial field.

  Electrical installations commonly include numerous components, which are supplied and protected by different circuits. The only conductor they have in common is the protective conductor. This must be connected to the body of the organs, this to guarantee a uniform potential, and to allow the protection organs (circuit breaker, differential, permanent insulation controller) to act or alert in the event of an insulation fault. . So according to current techniques

  the electrical devices and the protective conductor are connected.

  Today, in the event of a break in the protective conductor, the current protective bodies are blind, putting people in danger of death.

  simple physical contact with the electrical receiver.

  Indeed, in the absence of the protective conductor, the electrical receiver could be at the potential of one of the phases if it were to fail (poor insulation of an electrical component, or stripped electrical conductor

  touching the device envelope ...).

  In all cases of neutral regime distribution, the voltages generated in the event of insulation fault are 220 Volts. In IT regime (impedant neutral) the

  voltages generated on double faults can cause voltages of 380 Volts.

  The only insurance for the protection of persons on this double fault is the speed of tripping, on the imperative condition that the protective conductor

is connected.

  In the absence of this protective conductor on one of the two components

  in default, the contact voltage between these two members is 380 Volts.

  The intensity likely to pass through the person who would come into physical contact with

  these organs would be of the minimum caliber of the weakest circuit breaker.

  We can easily understand the danger when we know that from contact with

  75 milli Amperes the human heart reaches the threshold of irreversible fibrilation.

  For the protection of people, it is imperative to constantly check

the protective conductor.

  In the case of smoke extraction motors, an insulation check is carried out continuously, this in order to be sure that in the event of a fire the smoke extraction motors will start. Strictly nothing in the event of a protective conductor break

cannot be controlled.

  For this kind of problem, it is also imperative to check in

  the protective conductor.

  The only check carried out to date of this protective conductor is an annual check carried out by an authorized person and only in the premises subject to this compulsory check. Knowing that certain devices such as pumps

  submerged for example cannot be checked.

  The object of the present invention is to protect practically

infallible people.

  The present invention proposes to do this a system for permanently monitoring the connection and continuity of the protective conductor. It facilitates the control of the protective conductors over time, knowing that certain installations degrade rapidly (due to vibrations, constant movement. ...). The present invention consists in injecting a very low voltage electric current into the circuit of the protective conductor and recovering this current on the panels or receivers to be controlled. This information processed, if the conductor or equipotential links are absent or of poor quality

  of the circuit concerned is cut or the fault reported, as the case may be.

  The present invention consists in injecting a very low voltage current from terminal 1 connected to the protective conductor 9. The protective conductor 9 itself being systematically connected to the receiver 10, the term “receiver” means: any electrical device

  included in an installation it can therefore be single or multiple.

  The very low voltage current injected from terminal 1 to the receiver 10 is recovered by means of a return conductor II and transmitted to terminal 2 of the permanent controller of the

  protective conductor and equipotential bonding 8.

  The fact that the current from terminal 1 arrives at terminal 2 guarantees that the connections of the

  2 5 protective conductor 9 are effective.

  The presence of this current on terminal 2 allows the switching of terminals 3,4,5. The

  terminals 3, 4, 5 being servo terminals entering into a process.

  The present invention intervenes in the case of breakage of the protective conductor 9, the current from terminal 1 then no longer being able to be transmitted to terminal 2, the terminals 3,4,5

  3 0 return to the zero state cutting off the supply to the member 13.

  The present invention also intervenes in the event of a break in the conductor 11 or in the event of failure of the protection 12, the current of the terminal 1 can no longer be

transmitted to terminal 2.

  The attached drawing is given as an indicative and non-limiting example.

  It represents a preferred embodiment according to the invention. It will allow

  to easily understand the invention.

  Figure I shows an overview of a particular embodiment

of the installation.

REFERENCES

  1. very low voltage terminal 2. very low voltage terminal 3. servo terminal 4. servo terminal 5. servo terminal 6. supply terminal 7. supply terminal 8. permanent protective conductor controller and equipotential bonding 9. protective conductor 10. receiver to be checked II. return conductor 12. protection 13. circuit breaker

Claims (4)

  1. Device for monitoring the protective conductor, characterized in that it has: - a very low voltage terminal (1) connected to the protective conductor (9) - a very low voltage terminal (2) connected to the receiver to be monitored ( 10) - terminals (3) (4) (5) for the controls   - terminals (6) (7) for its power supply.   2. Device for monitoring the protective conductor according to claim 1, characterized in that the terminal (1) transmits a very low voltage current in the protective conductor (9) that the terminal (2) connected to the receiver (10) recovers. the current from the protective conductor (9) via a return conductor (l11) and transmits it to the permanent conductor controller of   protection and equipotential bonding (8).   3. Protective conductor monitoring device according to one of the   previous claims characterized in that the protective conductor current   guaranteed that the protective conductor (9) connections are effective and allows the   switching of terminals (3), (4) and (5) authorizing power-up.   4. Device for monitoring the protective conductor according to one of the   previous claims characterized in that in the event of rupture of one of the   conductor (9) or (11) or in the event of protection (12) being cut off, the terminals (3) (4) and (5) return to the zero state preventing or cutting off the power supply,   depending on the case, of the circuit breaker (13).