Main electrical protective equipment in electrical installations
Main electro protective equipment in electrical installations with voltages above 1000 V are insulating and electrical clamps, voltage indicators, as well as insulating devices and fixtures for repair work (platforms, insulating links of telescopic towers, etc.).
Insulating rods consist of three parts: working, which, depending on the purpose of the rod, is made in the form of a finger, grip, cutter, brush, etc.; insulating, which serves to isolate the worker from the current-carrying part (the length of the insulating part is determined by the operating voltage of the rod); handles for holding the bar in the hands.
Depending on destination rods are divided into operational, repair and measuring. Operational insulating rods intended for distribution operations; devices - switching on and off disconnector knives, checks, etc. Repair insulating rods are used to perform work on live parts under voltage (cleaning insulators from dust, connecting temporary electrical receivers, knitting wires, etc.). Measuring insulating rods used to control the distribution of voltage on individual insulators in garlands, as well as to measure the transient resistance of contact connections.
Work with a barbell is allowed only to specially trained personnel in the presence of a person who controls the actions of the worker. During operations with an insulating rod, it is necessary to use additional insulating protective equipment - dielectric gloves and insulating bases (supports, rugs) or dielectric bots.
Clamp meters designed to measure current without breaking the circuit. They consist of a current transformer with a split magnetic circuit and secondary winding loaded with an ammeter, as well as handles of the appropriate length. Currently, current clamps Ts90 (up to 10 kV) are used for current up to 600 A. The rules for using current clamps are the same as for insulating clamps.
Voltage indicators designed to determine the presence of voltage without measuring its value. Voltage indicators above 1000 V are manufactured in two modifications: with a gas-discharge indicator lamp, the principle of operation of which is based on the glow of a gas-discharge indicator lamp when a capacitive current flows through it, and non-contact type, which operate on the principle of electrostatic induction.
Voltage indicator with discharge lamp consists of a working, insulating part and a handle. The working part includes a tip contact, a gas discharge lamp, the burning of which indicates the presence of voltage on the part of the electrical installation being tested, and capacitors. Currently, UVN-10 and UVN-80M indicators are used (for electrical installations with a voltage of 2-10 kV) and UVN-90 (for electrical installations of 35-110 kV). Contactless pointer high voltage UVNB 6-35 kV is designed to determine the presence or absence of voltage on overhead lines, in closed switchgear and outdoor switchgear with a voltage of 6-35 kV. Its signal is an intermittent glow of an incandescent lamp, and the lamp flashing frequency increases as the pointer approaches live parts. The voltage signaling device of an individual SNI 6-10 kV is designed to warn a person about the presence of voltage when approaching the wires of a 6-10 kV overhead line at an unacceptable distance. Its signal is an intermittent sound, the interruption frequency increases as it approaches the zone of unacceptable distance, and in the zone itself, the indication turns into continuous sound; the signaling device belongs to additional electrical protective equipment and cannot be used instead of voltage indicators.
Insulating pliers used in electrical installations up to 35 kV for live operations with fuse links of tubular fuses, as well as for putting on and removing insulating caps on the knives of single-pole disconnectors.
When using insulating clamps, the operator must wear dielectric gloves and be isolated from the floor or ground; when changing tubular fuse holders, he must be wearing glasses. Ticks must be held in outstretched hands.
Additional electrical protective equipment in electrical installations
Additional insulating electrical protective equipment includes dielectric gloves, boots, rubber mats and tracks, insulating stands on porcelain insulators and portable grounding.
Portable grounding are used to protect people working on disconnected current-carrying parts from erroneously applied or induced voltage. They consist of clamps for connecting to grounded wires, a grounding conductor for grounding and shorting between each other the current-carrying parts of all phases of the installation and a lug or clamp for connecting to a grounding conductor or grounded structures.
Portable grounding with the help of special conductors and clamps short-circuit current-carrying parts and connect them to the ground. They are made from flexible copper wire with a core cross section designed for thermal stability when currents flow short circuit, but not less than 25 and 16 mm2 for electrical installations above 1000 V and up to 1000 V, respectively.
Portable ground overlay perform in the following sequence: first, the grounding conductor is connected to the grounding device, and then the shorting conductors are applied to the phase wires. Remove the portable grounding in reverse order. The operator performs operations with portable grounding using an insulating rod in dielectric gloves, standing on an insulating base (mat or stand) or in dielectric boots.
In electrical installations with voltages above 1000 V, when performing an inspection by one person, it is prohibited to penetrate the fences, enter the switchgear chambers that do not have barriers, and enter the explosive chambers of oil switches. Inspection of the cells should be carried out from the threshold or standing in front of the barrier. In case of emergency, it is allowed to enter the chamber for inspection, but only in the presence of a second person and on condition that the person performing the inspection will be at a safe distance from live parts.
Inspections can be made individually:
a) administrative and technical personnel of group V;
b) operational personnel not lower than group III.
One person view switchgears allowed, provided that the lower flanges of the insulators, on which the current-carrying parts are fixed, are at a distance of at least 2 m from the floor, and unshielded current-carrying parts located above the passage with a voltage of up to 35 kV are at a distance of at least 2.75 m. - Do not work on or near the equipment.
If a connection of any current-carrying part of the electrical installation with the ground is detected, it is prohibited to approach the place of such damage at a distance of less than 4-5 m in closed switchgears and 8-10 m at open substations until disconnected.
Approach to a closer distance is allowed only if it is necessary to carry out operations with switching equipment to eliminate a ground fault, as well as to provide the necessary assistance to the victims. In these cases, it is imperative to use protective equipment and strictly follow the Rules for the provision of first aid to victims of electric current.
Maintenance of electrical installations is carried out by on-duty personnel, and in electrical installations without constant duty by operational and repair personnel (operational personnel). At the same time, the latter may be assigned the rights and obligations of duty personnel in relation to operational work, inspection of electrical installations, preparation of the workplace and admission of teams to work in accordance with the requirements of the Rules.
The type of operational service and the number of personnel in a shift or at an electrical installation assigned to him is determined by the head of the electrical department or the head of the substation in agreement with the chief power engineer of the enterprise. The qualifications of operational personnel who solely serve electrical installations and seniors in a shift must be at least group IV.
During the production of switching, one of the attendants controls the correctness and sequence of operations performed by another, junior officer on duty. Responsibility for the correct operation lies with both persons.
A single person on duty can switch only if there is an interlock between the switches and disconnectors, which ensures the correct sequence and safety of operations (figure). Switching on and off of switches is carried out individually.
To eliminate the possibility of erroneous operations with disconnectors in switchgears and substations, interlocking of the disconnector drive with the circuit breaker drive should be provided.
In simple circuits, mechanical interlocks are usually used (Figure 1)
and with a double busbar system, electromagnetic interlocks (Figure 2).
Key K can be removed from lock 1 (Figure 3) at the circuit breaker only after switching off
circuit breaker when solenoid engagement C is not connected to switch rod B. If the key is removed, the circuit breaker is locked and cannot be closed. The key K unlocks the locks 2 and 3 of the busbar P1 and linear P2 disconnectors. The key from the locks of the disconnectors can only be removed when they are in their extreme position, i.e., on or off.
After operations with disconnectors, the key K is inserted into the lock 1 of the switch, which can be turned on.
To turn on the coil of the electromagnetic key, each drive lock has two K contacts. A "minus" is connected to one contact K directly from the power source, and a "plus" is supplied to the other contact K through the corresponding auxiliary contacts of the switch B and the disconnector. If, for example, the busbar disconnector P1 and the electromagnetic key inserted into the lock in this position are energized, pulls the pin T and makes it possible to operate with the disconnectors P2 and P3. When the switch is on, the key is de-energized and the current circuit of the key coil is broken by the auxiliary contacts of the switch, so operations with the disconnector are impossible, since the lock is locked. Disconnector P1 is blocked in the same way.
The lock must be unlocked before the disconnector can be switched on or off. This operation is performed using a portable electromagnetic key.
Turning on and off disconnectors with an insulating bar, switches and disconnectors with a manual drive, checking the absence of voltage and the serviceability of the voltage indicator, changing fuses must be done with dielectric gloves on. When changing fuses, insulating pliers and safety goggles must also be used.
Questions on preparing for the knowledge test with those responsible for the electrical economy, their deputies (for consumers with electrical installations with voltages above 1000 V)
1. The appointment of a person responsible for electrical equipment in installations with voltages above 1000 V is made after ...
Knowledge checks and assignment of an electrical safety group:
5- in electrical installations with voltage over 1000 V,
4- in electrical installations with voltage up to 1000 V.
2. What does not apply to the main electrical protective equipment used in electrical installations with voltage up to 1000 V?
Dielectric galoshes
Dielectric rubber mats
Insulating pads
Fixed assets:
Dielectric gloves
Tools with insulated handles
Voltage indicators, insulating clamps.
3. In installations up to what voltage class (kV), inclusive, upon admission to work, does the permitter prove to the brigade that there is no voltage by touching the live parts with his hand (after preliminary checking the absence of voltage with a pointer or rod)?
Up to 35 kV
4. What electrical safety group should have employees from among the operational personnel who solely serve electrical installations with voltages above 1000 V?
4 group
5. How often should inspections of switchgears be carried out without shutting down, at facilities without constant personnel on duty?
At least once a month
6. In what cases is it allowed to use round steel as grounding conductors on overhead lines up to 1 kV?
It is allowed to use round steel Ø at least 6 mm, having an anti-corrosion coating, galvanized steel Ø at least 12 mm
7. To whom is the order given?
To the manufacturer of works and allowing
8. To protect against defeat electric shock in normal operation, the following measures of protection against direct contact should be applied individually or in combination: basic insulation of live parts, fences and enclosures, installation of barriers ...., use of extra low (low) voltage (Complete answer)
Placement out of reach
9. Responsible for the electrical economy is obliged to ensure the revision of instructions and diagrams at least ...
1 time in 3 years
10. What is unacceptable to do in cases of electric shock?
Stop resuscitation until signs of biological death appear
11. What is the nominal voltage deviation of the most distant lamps in the internal working lighting network?
No more than 5% of the nominal, in the network 12 - 50V no more than 10% of the nominal
12. Is it a mandatory form of work with repair personnel?
Introductory, primary at the workplace, repeated, unscheduled and targeted briefings on labor protection,
Internship,
Checking knowledge of the rules, labor protection standards, rules technical operation electrical installations of consumers, fire safety rules,
Coordinate the project with the energy supply organization and the state energy supervision authority
P1.3.2 POT c19
59. What electrical protective equipment does not apply to additional electrical installations with voltage up to 1000 V?
Dielectric gloves
Tool with insulating handles
Voltage gauges, insulating clamps
60. Who is responsible for the correct and timely investigation and accounting of accidents that occurred in electrical installations, execution of acts, development and implementation of measures to eliminate the causes of an accident?
Enterprise manager
61. Is it allowed to replace fuses (except plug type) under voltage?
Energized but not loaded
In secondary circuits (under voltage and under load)
Voltage fuses (live and loaded)
62. Who is responsible for compliance with the measures to ensure the safety of work performance, provided for by the act - admission, during the work of construction and installation organizations (CMOs) in existing electrical installations?
Heads of the CMO and the organization in which the work is carried out
63. How many connections on each wire or cable overhead lines(VL) is allowed during operation in the spans of the intersection of an existing overhead line passing from above another overhead line?
No more than 1 connection
64. In what cases is an employee's primary knowledge test performed?
For the first time, they entered the work related to the maintenance of electrical installations
Break in knowledge testing for more than 3 years
65. What is the shortest distance that people and the tools and devices they use are not allowed to approach energized unshielded live parts of 1-35 kV electrical installations?
66. What safety measures are applied in the presence of metal reflectors in luminaires with housings made of insulating materials?
Not required
67. What is not allowed to be used as PE conductors?
Metal sheaths of insulating tubes
Support cables
Metal hose
Lead sheaths of wires and cables
74. What is allowed to be used as a PE conductor?
veins multicore cables, insulated or uninsulated wires in one sheath with phase, aluminum cable sheaths, steel pipes for electrical wiring, metal sheaths and busbar support structures, metal and building structures of buildings, metal structures for industrial purposes
75. What voltage electrical installations are covered by the work performed in the order of current operation (list of works)?
Up to 1000 V.
76. What electrical safety group should be for labor protection specialists inspecting the electrical installations of their enterprise?
4th group with the right to inspect
77. The appointment of a person responsible for electrical equipment in electrical installations with voltages above 1000V is made after ...
Knowledge checks in the Energy Supervision Commission
78. What is the maximum length of the connecting flexible cable from the switching device to the portable (mobile) electric welding unit?
79. What is indicated on a tag attached to a portable ground or clamp?
U nom
Wire section
Inventory number
80. Is it allowed to remove the groundings installed in the switchgear during the preparation of the workplace?
81. Who is obliged to immediately notify the Consumer in cases of defects or failures in the operation of calculated electric energy meters?
Energy supply organization
82. How often should the presence and condition of protective equipment be checked by an inspection by an employee responsible for their condition with recording the results of the inspection in a journal?
At least 1 time in 6 months.
83. Who should conduct the initial briefing of seconded personnel?
An employee from among the administrative and technical personnel with a tolerance group of at least 5 in installations above 1000V, not lower than 4 in installations up to 1000V
84. Who should seal the cover of the terminal block of the verified settlement meter?
Energy supply organization
85. In installations with a dead-earthed neutral with a voltage of 380/220 V, the permissible resistance of the grounding devices of electrical installations (excluding re-grounding of the neutral wire) should be no more than ...
86. What are the requirements for socket outlets installed in buildings when using a three-wire network?
With grounding contact for a current of at least 10 A
87. What determines the duration of the order?
The length of the working day of the performer
88. What is the foreman responsible for?
For the compliance of the workplace with the instructions of the order; for the completeness of the targeted briefing of the members of the brigade; for the availability, serviceability and correct use of protective equipment, tools, inventory and devices; for the safety of fences, posters, grounding; for safe work and compliance with safety rules
89. What is the minimum insulation resistance of the stator windings of electric motors alternating current voltage up to 1000 V (at a temperature of 10-30)?
Not less than 1 mΩ
90. What is the permissible duration of urgent work performed by order in email. installations above 1000 V?
No more than 1 hour, excluding preparation time
91. Under what conditions may a knowledge test be not carried out for a specialist hired part-time in order to impose on him the duties of a person responsible for electrical facilities?
If the level of complexity of electrical facilities at another place of work is higher
92 How long is a work permit issued for?
No more than 15 calendar days from the date of commencement of work
93. Who is responsible for the safety of groundings installed at the workplace?
94. In which commission should the knowledge of the electrical and electrical personnel of the Consumer be tested?
In the enterprise commission
95. How long should the outfits, the work on which is completely completed, be stored, after which they can be destroyed?
Within 30 days, in case of an accident or an accident in the archives of the enterprise, together with an investigation report, 45 years
96. What is the frequency of inspections of grounding devices with selective opening of the soil in places most susceptible to corrosion, as well as near the grounding points of transformer neutrals?
1 time in 12 years
97. Is it allowed to perform any work during the inspection of electrical installations?
98. Is it allowed to use third-party conductive parts as the only PEN conductor?
Not allowed
99. What is the minimum allowable insulation resistance of switchgear electrical equipment elements up to 1000 V?
1 MΩ
100. At what distance from the end of the tip of the screwdriver should the insulation of the screwdriver shaft end?
