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ENCYCLOPEDIA OF RADIO ELECTRONICS AND ELECTRICAL ENGINEERING
Section 3. Protection and automation Automation and telemechanics. Automatic switching on of standby power and equipment (ATS)
Encyclopedia of radio electronics and electrical engineering / Rules for the installation of electrical installations (PUE) 3.3.30. ATS devices should be provided for restoring power to consumers by automatically connecting a backup power source when the working power source is turned off, leading to a blackout of the consumer's electrical installations. ATS devices should also be provided for automatically turning on standby equipment when the working equipment is turned off, leading to a disruption in the normal technological process. ATS devices are also recommended to be provided if their application can simplify relay protection, reduce short-circuit currents and reduce the cost of equipment by replacing ring networks with radially sectioned ones, etc. ATS devices can be installed on transformers, lines, sectional and bus-connecting switches, electric motors, etc. 3.3.31. The ATS device, as a rule, should ensure the possibility of its operation in the event of a voltage failure on the buses of the fed element, caused by any reason, including a short circuit on these buses (the latter - in the absence of AVR tires, see also 3.3.42). 3.3.32. When the switch of the working power source is turned off, the ATS device shall switch on, as a rule, without additional time delay, the switch of the reserve power source (see also 3.3.41). In this case, a single operation of the device must be ensured. 3.3.33. To ensure the operation of the ATS when the powered element is de-energized due to a power failure on the power supply side of the working source, as well as when the switch is turned off on the receiving side (for example, for cases when the relay protection of the working element only acts to turn off the switches on the supply side) in the ATS circuit in addition to that specified in 3.3.32, a starting voltage element shall be provided. The specified triggering element in the event of a power failure on the fed element and in the presence of voltage from the power supply side of the backup source must act with a time delay to turn off the switch of the working power source on the receiving side. The ATS starting voltage element should not be provided if the working and reserve elements have the same power source. 3.3.34. For short-range transformers and lines, in order to speed up the action of the ATS, it is advisable to perform relay protection with an action to turn off not only the circuit breaker on the supply side, but also the circuit breaker on the receiving side. For the same purpose, in the most critical cases (for example, for the own needs of power plants), when the circuit breaker is turned off for some reason only on the supply side, the circuit breaker must be immediately disconnected from the receiving side via the blocking circuit. 3.3.35. The minimum voltage element of the ATS triggering element, which reacts to the loss of voltage of the working source, must be detuned from the mode of self-starting of electric motors and from voltage reduction during remote short circuits. The response voltage of the voltage control element on the buses of the backup source of the ATS starting body should be selected, if possible, based on the condition of self-starting of the electric motors. The time of action of the starting element of the ATS should be longer than the time of disconnection of external short circuits, at which a voltage drop causes the undervoltage element of the starting element to operate, and, as a rule, more than the time of action of the automatic reclosure on the supply side. The minimum voltage element of the ATS starting body, as a rule, must be designed so that its false operation is excluded when one of the fuses of the voltage transformer burns out from the side of the high or low voltage winding; when protecting the low voltage winding with a circuit breaker, when it is turned off, the action of the starting element must be blocked. It is allowed not to take into account this requirement when performing AVR devices in 6-10 kV distribution networks, if this requires a special installation of a voltage transformer. 3.3.36. If, when using the ATS start by voltage, the time of its action may turn out to be unacceptably long (for example, if there is a significant proportion of synchronous electric motors in the load), it is recommended to use other types of starting elements in addition to the starting voltage element (for example, reacting to the loss of current, reducing the frequency , power direction change, etc.). In the case of using a starting frequency control, the latter, when the frequency decreases from the side of the working power source to the set value and at normal frequency from the side of the backup power supply, must act with a time delay to turn off the switch of the working power source. If technologically necessary, a device for automatically switching on standby equipment can be started from various special sensors (pressure, level, etc.). 3.3.37. The scheme of the AVR device for auxiliary power supplies of power plants after turning on the backup power source instead of one of the switched off working sources should retain the ability to operate when other working power sources are turned off. 3.3.38. When performing ATS devices, it is necessary to check the conditions for overloading the backup power source and self-starting of electric motors and, if there is an excessive overload or self-starting is not provided, perform unloading during the action of ATS (for example, turning off non-responsible, and in some cases, parts of critical electric motors; for the latter, it is recommended to use APW). 3.3.39. When performing ATS, the inadmissibility of its action to turn on consumers disconnected by AChD devices should be taken into account. For this purpose, special measures should be applied (for example, blocking by frequency); in some cases, with a special justification for the impossibility of carrying out these measures, it is allowed not to provide for ATS. 3.3.40. During the operation of the ATS device, when it is possible to turn on the circuit breaker on a short circuit, as a rule, acceleration of the protection action of this circuit breaker should be provided (see also 3.3.4). At the same time, measures must be taken to prevent disconnections of the backup power supply through the protection acceleration circuit due to inrush currents. To this end, on the circuit breakers of backup power supplies for auxiliary needs of power plants, protection acceleration should be provided only if its time delay exceeds 1-1,2 s; in this case, a time delay of about 0,5 s must be introduced into the acceleration circuit. For other electrical installations, the time delay values are taken based on specific conditions. 3.3.41. In cases where, as a result of the action of the ATS, non-synchronous switching on of synchronous compensators or synchronous electric motors is possible and if it is unacceptable for them, as well as to exclude recharge from these machines of the damage site, it is necessary to automatically turn off the synchronous machines in the event of a power failure or transfer them to asynchronous mode by turning off the AHS with subsequent automatic switching on or resynchronization after voltage recovery as a result of a successful ATS. To prevent switching on the backup source from the ATS before the synchronous machines are switched off, it is allowed to apply the deceleration of the ATS. If the latter is unacceptable for the rest of the load, it is allowed, with special justification, to disconnect from the ATS starting body the line connecting the operating power buses with the load containing synchronous electric motors. For substations with synchronous compensators or synchronous motors, measures must be taken to prevent incorrect operation of the AFC when AVR is in operation (see 3.3.79). 3.3.42. In order to prevent the backup power source from switching on to a short circuit with an implicit reserve, to prevent its overload, to facilitate self-starting, as well as to restore the normal circuit of the electrical installation by the simplest means after an emergency shutdown and the operation of an automation device, it is recommended to use a combination of AVR and AR devices. AVR devices must operate in case of internal damage to the working source, automatic reclosure - in case of other damage. After the successful operation of the automatic reclosure or automatic reclosure devices, as a rule, the most complete automatic restoration of the pre-emergency mode circuit should be ensured (for example, for substations with simplified electrical connection diagrams on the higher voltage side, switching off the sectional switch switched on during the action of the ATS on the low voltage side after a successful automatic reclosure supply line).
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