6.2.4. Operational switching in electrical installations
One of the most complex and responsible tasks that requires a thorough knowledge of the power supply circuit of an electrical installation is the production of operational switching. Switchings are made in connection with the preparation of workplaces for performing various kinds of work in an electrical installation (installation, commissioning, repair, etc.), to ensure a reliable, economical and safe power supply to production, and for a number of other reasons related to operational dispatch control in the power system.
In the production of operational switching, there should be a clear delineation of responsibilities for all parts of the operational and dispatching personnel. Switchings are carried out by order or with the knowledge of higher operational personnel in whose operational management or jurisdiction this electrical equipment is located. In accordance with the user's electrical energy in order, this may be an oral or telephone order with an entry in the operational log.
Order No. 266 of the Ministry of Energy of Russia dated June 30, 2003 approved the Instructions for Switching in Electrical Installations, which determines the procedure and sequence for performing switching in electrical installations with voltages up to and above 1000 V.
The instruction was drawn up in accordance with federal law, PTE power stations and networks, labor protection rules.
On the basis of the specified instruction at power plants, in electrical networks and at other facilities, local instructions for the production of switching should be developed, taking into account the features of normal and repair schemes for electrical connections of electrical installations, the design and composition of the switchgear equipment, the features of the relay protection device, and the procedure for the operational maintenance of these facilities. The instructions should reflect the features and procedure for switching during the operational maintenance of electrical equipment.
The content of the switching order and the procedure for its implementation are determined by the higher-level operational personnel issuing it, taking into account the complexity of the task, the necessary coordination of the actions of the operational personnel and the consistency of changes in electrical installation diagrams. The order indicates the purpose of switching and the sequence of operations in the electrical installation diagram and relay protection and automation circuits with the required degree of detail, determined by higher-level operational and dispatching personnel.
At power plants and substations with constant duty of operational personnel, the switching performer is simultaneously given no more than one task for conducting operational switching, containing operations of the same purpose.
When repairing damages in electrical networks with a voltage of 10 kV and below, it is allowed to perform the next tasks without prior notification to the dispatcher about the completion of the previous tasks.
The dispatcher's order to switch is considered fulfilled if the person who received the order informed the dispatcher about its execution.
Operational switching must be performed by an employee from among the operational personnel directly servicing electrical installations. Complex switching, as well as all switching (except for single ones) on electrical installations that are not equipped with interlocking devices or have faulty interlocking devices, must be carried out according to programs or switching forms.
For complex transitions include switching that requires a strict sequence of operations with switching devices, grounding disconnectors and relay protection devices. Lists of complex switching, approved by the technical manager of the enterprise (organization), technical managers of the relevant AO-energy and power facilities, should be stored at control rooms, central (main) control panels of power plants and substations.
Switching form (regular) is an operational document that provides a strict sequence of operations with switching devices, grounding disconnectors (knives), operating current circuits, relay protection devices, operations to check the absence of voltage, apply and remove portable grounding, hang and remove posters, as well as necessary (according to conditions of personnel safety and safety of equipment) verification operations.
Typical switching form is an operational document that indicates a strict sequence of operations when performing repetitive complex switching in electrical installations for specific electrical connection diagrams and states of relay protection devices.
When performing complex switching, it is not allowed to replace forms or switching programs with any other documents.
The switching forms indicate the most important verification actions of personnel:
checking the absence of voltage before applying grounding (turning on grounding knives) to live parts;
on-site check of the switched on position of the bus connection switch before starting operations to transfer connections from one bus system to another;
on-site verification of the open position of the circuit breaker, if the next operation is with disconnectors;
verification on site or by means of signaling devices of the position of each switching device of the primary circuit after the operation is performed by this device;
checking after the end of the switching of the conformity of the switching devices in the RPA circuits to the regime cards.
The instruction strictly regulates the rules and procedures for the application, execution, storage and reporting when using the switching forms. Each operation or action in the switching form is recorded under a serial number (Appendix 5). The switch forms themselves must be numbered. Used switching forms are stored in accordance with the established procedure for at least 10 days.
Along with the general provisions on switching, the instructions contain the requirements and procedure for the production of operational switching in relay protection circuits, when eliminating technological violations, when putting new equipment into operation and conducting tests. The sequence of operations with switches, disconnectors, separators and load switches, as well as with switching devices for line connections, transformers, synchronous compensators and generators is given. The switching order is considered when transferring connections from one bus system to another, when equipment is taken out for repair and when it is put into operation after repair, etc.
When describing switching in distribution networks, in addition to the features of switching and general instructions for their implementation, a sequence of operations is given when performing certain specific types of switching. It is necessary to know and strictly follow the sequence of these operations.
In Appendix 6, as an example, the sequence of basic operations is given when the supply cable is put into repair, and in Appendix 7 - the sequence of basic operations when it is put into operation after repair.
Electricity consumers should have lists of complex switching approved by the technical manager of the organization, which should be stored at control rooms, central (main) control panels of power plants and substations.
Complex switching should be performed, as a rule, by two employees, of which one is the supervisor.
Switching in electrical installations of different levels of control and different objects is carried out according to switching programs (typical programs).
Switching program (typical program) is an operational document that indicates a strict sequence of operations when switching in electrical installations of different levels of control or different power facilities.
The switching program is approved by the head of the dispatching department, in whose operational subordination is all the switched equipment.
If there is only one employee from among the operational personnel on the shift, an employee from the administrative and technical personnel who knows the scheme of this electrical installation, the rules for making switching and is allowed to perform them can be the supervisor.
In emergency cases (accident, natural disaster), as well as during the liquidation of accidents, it is allowed, in accordance with local instructions, to perform switching without an order or without the knowledge of higher operational personnel, followed by its notification and entry in the operational log.
Switching in an electrical installation is allowed to be performed by operating personnel who know its scheme, the location of equipment and relay protection devices, who are trained in the rules for performing operations with switching devices and clearly represent the sequence of switching, who have passed the knowledge test of PTE, safety rules and instructions. Admission to operational work is allowed after duplication at the workplace.
The list of employees allowed to carry out switching (with an indication of which electrical installations), as well as the list of administrative and technical personnel who control the implementation of switching, is approved by the head of the enterprise (organization).
The list of employees who have the right to conduct operational negotiations is approved by those responsible for the electrical economy and transferred to the energy supply organization and sub-subscribers.
In accordance with the PTEEP, in the programs and forms of switching, which are operational documents, the procedure and sequence of operations should be established when switching in the electrical connection diagrams of electrical installations and relay protection and automation circuits.
Switching programs (standard programs) should be used by the heads of operational personnel when switching in electrical installations of different levels of management and different power facilities. Employees who directly perform switching are allowed to use the switching programs of the corresponding dispatcher, supplemented by switching forms.
In electrical installations with voltages above 1000 V, switching is carried out:
without switching forms - for simple switching and in the presence of active interlocking devices that exclude incorrect operations with disconnectors and grounding knives during all switching;
according to the switching form - in the absence of blocking devices or their malfunction, as well as in case of complex switching.
Without forms, but with a subsequent entry in the operational log, switching is carried out during the elimination of accidents.
In electrical installations with voltages up to 1000 V, switching is carried out without compiling forms, but with an entry in the operational log.
When switching in PTEEP electrical installations, the following procedure is required:
the employee who has received the assignment for switching is obliged to repeat it, write it down in the operational log and establish the order of upcoming operations according to the operational scheme or layout scheme, draw up, if necessary, a switching form. Negotiations of operational personnel should be as short and clear as possible;
if switching is performed by two employees, then the one who received the order is obliged to explain the order and sequence of upcoming operations to the second employee participating in the switching according to the operational connection diagram;
if there is any doubt about the correctness of the switching, they should be stopped and the required sequence checked according to the operational wiring diagram;
after completing the task for switching, an entry about this should be made in the operational log.
Operational personnel directly performing the switching are prohibited from arbitrarily disabling the blocking.
In accordance with the requirements of the PUE, all switchgear must be equipped with an operational blocking of incorrect actions when switching in electrical installations, designed to prevent incorrect actions with disconnectors, grounding knives, separators and short circuits.
Operational blocking should exclude:
voltage supply by a disconnector to the section of the electrical circuit grounded by the switched on grounding switch (grounding knife), as well as to the section of the electrical circuit separated from the switched on grounding switches only by a switch;
the inclusion of a grounding switch in a section of the circuit that is not separated by a disconnector from other sections, which can be both energized and without voltage;
opening and closing by a load current disconnector.
Operational blocking should provide in a circuit with a series connection of a disconnector with a separator, the switching on of an unloaded transformer by the disconnector, and disconnection - by the separator.
Unblocking is allowed only after checking on site the disconnected position of the circuit breaker and finding out the reason for the failure of the blocking by permission and under the guidance of employees authorized to do so by a written order of the consumer responsible for the electrical economy.
When switching in electrical installations, operations for the imposition and removal of portable grounding almost always take place. Operating personnel performing operations with portable grounding must comply with the following provisions of the instruction.
Portable grounding must be numbered through the entire electrical installation by numbering and stored in certain places designated for this purpose, the numbering of which must correspond to the number available on the portable grounding.
To save time on records when passing duty, it is recommended to use a special stamp for recording portable grounding, affixed in the operational journal, for example, as shown in Table. 6.2.
Table 6.2
Stamp accounting for portable grounding and a record of their location
Grounding No. 1, 2 - under repair.
Grounding No. 40 is installed in cell 15 on CL5.
When equipment is taken out for repair and grounded, stationary grounding knives are switched on first, and then (if necessary) portable groundings are applied. When the equipment is put into operation after repair, all portable grounding devices are first removed and placed in storage places, and then stationary grounding knives are turned off.
The switching form is filled in by the person on duty who received the order to carry them out. The form is signed by both employees who carried out the switching. Supervising when performing switching is the senior in position. Responsibility for the correct switching in all cases lies with both employees who performed the operations.
Disconnection and inclusion under voltage and into operation of the connection, which has a switch in its circuit, must be carried out using a switch.
It is allowed to switch off and on by separators, disconnectors, detachable contacts of KRU (KRUN) connections:
neutrals of power transformers with a voltage of 110–220 kV;
grounding arc-suppressing reactors with a voltage of 6-35 kV in the absence of a ground fault in the network;
magnetizing current of power transformers with a voltage of 6-220 kV;
charging current and earth fault current of overhead and cable power lines;
charging current of busbar systems, as well as charging current of connections in compliance with the requirements of regulatory and technical documents of the power supply organization.
In ring networks with a voltage of 6-10 kV, it is allowed to switch off circulating currents up to 70 A by disconnectors and close the network into a ring when the voltage difference at the open contacts of the disconnectors is not more than 5% of the rated voltage.
It is allowed to switch off and on the load current up to 15 A by three-pole outdoor disconnectors at a voltage of 10 kV and below.
Remote disconnection of a faulty 220 kV circuit breaker shunted by one circuit breaker or a chain of several circuit breakers of other connections of the busbar system is allowed if disconnection of the circuit breaker can lead to its destruction and de-energization of the substation.
Permissible values of currents switched off and on by disconnectors must be determined by the regulatory and technical documents of the power supply organization.
The procedure and conditions for performing operations for various electrical installations must be regulated by local instructions.
As switching devices for the production of operational switching (manual or automatic switching on and off), switches are mainly used. Circuit breakers with arc extinguishing devices are designed to turn on or off sections in the circuit through which the load current, no-load current or short circuit current (short circuit) passes.
Disconnectors are also designed for manual or automatic switching on or off, but de-energized sections of the circuit; they are allowed to do the following:
switching on and off of the charging current (transient and alternating steady current through capacities of all types) of busbars and equipment of all voltage classes (except for the current of power capacitor banks);
switching on and off of voltage transformers, neutrals of power transformers and arcing reactors with a rated voltage of up to 35 kV inclusive in the absence of a phase-to-earth fault or resonance in the network;
switching on and off voltage transformers of electromagnetic type with a rated voltage of 110 kV and above;
shunting and deshunting of switched-on circuit breakers (from the drives of which the operational current is removed) together with the busbar adjacent to them.
When switching in electrical installations, it is necessary to follow a certain sequence, avoiding the slightest errors that can lead to emergencies in electrical installations and electrical injuries.
This can happen, for example, during operational switching in networks with a voltage of 6-10 kV due to non-compliance with a certain sequence of operations with disconnectors and switches. The consequences of erroneous switching on or off by disconnectors depend on which disconnectors (bus or linear) operate. The first to be switched on, and the last to be switched off, are those disconnectors, the incorrect operation of which can lead to more serious consequences.
For example, the sequence of typical operations with switching devices when turning on and off the connections of overhead lines and cable lines should be as follows.
Inclusion:
the open position of the switch is checked; the bus disconnector is switched on;
the line disconnector is switched on;
the switch turns on.
Shutdown:
the switch is turned off;
the line disconnector is turned off; the bus disconnector is switched off.
The sequence of operations in switchgear with withdrawable elements when switching on the connections of overhead lines and CLs should be as follows.
Inclusion:
checks if the switch is off;
the circuit breaker trolley moves from the control to the working position;
the switch turns on. Shutdown:
the switch is turned off; checks if the switch is off;
the trolley with the switch is moved to the control or repair position.
Disconnection of sectional disconnectors that are not interlocked with sectional switches (or in the absence of the latter) is carried out after removing the load from the disconnected busbar system and providing disconnectors with a visible break not only from the side of the supply connections, but also from the side of the outgoing feeders.
Despite the fact that the procedure for performing operational switching in electrical installations has remained unchanged for many years and has been worked out in detail, the readiness and safety of its implementation is largely determined by the level of organization of such work, the completeness and quality of the above regulatory operational dispatch documentation, the degree of responsibility and professionalism of the operational personnel of electrical installations of consumers and power supply organizations.
SO 153-34.20.505-2003
The instruction defines the order and sequence of switching in electrical installations with voltage up to 1000 V and above. The instruction is drawn up in accordance with federal legislation, rules technical operation power stations and networks, labor protection rules. On the basis of this Instruction, at power plants, in electrical networks, local instructions for the production of switching should be developed, taking into account the features of normal and repair schemes for electrical connections of electrical installations, the design and composition of switchgear equipment, features of the relay protection device, and the procedure for the operational maintenance of these objects.
The instruction was approved and put into effect by the Order of the Ministry of Energy of Russia dated June 30, 2003 N 266.
Document Format: .doc(MS Word)
1. GENERAL
2. ORGANIZATION AND PROCEDURE OF SWITCHING
2.1. Switch order
2.2. Switch forms
2.3. General provisions about switching
2.4. Switching in relay protection and automation circuits
2.5. Switching during the elimination of technological violations
2.6. Switchovers during commissioning of new equipment and testing
3. PERFORMING SWITCHES
3.1. Carrying out operations with switches, disconnectors, separators and switch-disconnectors
3.2. Removal of operational current from the drives of switching devices
3.3. Checking the positions of switching devices
3.4. Actions with hot blocking
3.5. The sequence of operations with switching devices of line connections, transformers, synchronous compensators and generators
3.6. Sequence of operations when switching on and off power lines
4. SWITCHING DURING THE TRANSFER OF CONNECTIONS FROM ONE BUS SYSTEM TO ANOTHER
5. SWITCHING WHEN THE EQUIPMENT IS STARTED FOR REPAIR AND WHEN THE EQUIPMENT IS PUT INTO OPERATION AFTER REPAIR
6. METHODS FOR REPAIRING AND PUTTING INTO OPERATION AFTER REPAIR OF SWITCHES
7. SWITCHING IN THE POWER DISTRIBUTION NETWORKS
7.1. Features of switching
7.2. General switching instructions
7.3. Sequence of operations when executing certain types switching
Annex 1. ACCOUNTING, APPLICATION AND REMOVAL OF GROUNDINGS
Appendix 2 MAINTAINING THE OPERATIONAL DIAGRAM AND LAYOUT DIAGRAM OF ELECTRICAL CONNECTIONS OF POWER PLANTS AND SUBSTATIONS
Appendix 3 SWITCHING IN DISTRIBUTION POWER NETWORKS OF 0.4 KV SUPPLYING ELECTRICAL INSTALLATIONS OF CONSUMERS WITH RESERVE POWER PLANTS
I couldn't find a table of contents in the instructions itself, so I compiled it myself.
