Power transformer operating procedures
Power transformer operating procedures
Generally, when we use Power Transformers, we will be subject to many requirements. At this time, we need to understand the operating procedures of power transformers to more familiar applications. Let's take a closer look.
1. The basic requirements and operating mode requirements for the operation of power transformers (hereinafter referred to as transformers). It can be used for the basic requirements, operation mode, operation and maintenance, abnormal operation and treatment of power transformer (hereinafter referred to as transformer), as well as installation, maintenance, test and acceptance requirements.
2. Execute the standard to view relevant information of the state regulations.
3.1 Protection, measurement, cooling device
3.1.1 Transformers shall be equipped with protection and measuring devices in accordance with the relevant standards.
3.1.2 The safety protection device, cooling device, oil protection device, temperature measuring device, fuel tank and accessories of the oil-immersed transformer body shall meet the requirements of GB6451. The dry transformer related equipment should meet the corresponding technical requirements.
3.1.3 When the transformer is protected by a fuse, the performance of the fuse must meet the requirements of system short-circuit capacity, sensitivity and selectivity. When the graded insulation transformer is protected by a fuse, the neutral point must be directly grounded.
3.1.4 Oil-immersed transformers equipped with gas relays, if there is no elevation gradient, the top cover should be installed with a gradient of 1% to 1.5% along the direction of the gas relay.
3.1.5 The cooling device of the transformer shall meet the following requirements:
a. Install all cooling units as specified by the manufacturer;
b. The cooling system for strong oil circulation must have two independent operating power supplies and can be switched automatically. When the working power supply fails, the standby power supply should be put into operation and an audio and light signal should be sent;
c. Strong oil circulation transformer, when the faulty cooler is cut off, it should emit sound and light signals, and automatically (water-cooled can be manually) put into the standby cooler;
d. The auxiliary motor of the fan, water pump and oil pump shall have overload, short circuit and phase failure protection; there shall be means for monitoring the direction of rotation of the oil pump motor;
e. The oil pump of the water cooler shall be installed on the oil inlet side of the cooler and ensure that the oil pressure in the cooler is greater than the water pressure of approximately 0.05 MPa in any case (except as otherwise specified by the manufacturer). There should be a drain cock on the outlet side of the cooler;
f. For transformers with strong oil circulating water cooling, the outlet of the submersible pump of each cooler shall be equipped with a check valve;
g. A transformer with a strong oil circulation cooling shall be capable of controlling the switching of the cooler by temperature and/or load.
3.1.6 Transformer should be equipped with temperature measuring device according to the following regulations: DL/T572-95
a. There should be a thermometer for measuring the top oil temperature (the transformer on the column may not be installed), and the transformer in the unattended substation should be equipped with a thermometer indicating a higher value of the top oil temperature;
b. Oil-immersed transformers of 1000kVA and above, oil-immersed type of 800kVA and above, and dry factory transformers of 630kVA and above, the signal thermometer shall be connected to the remote signal;
c. 8000kVA and above transformers should be equipped with remote temperature measuring devices;
d. Transformers with strong oil circulating water cooling shall be equipped with temperature measuring devices at the inlet and outlet of the cooler respectively;
e. When measuring temperature, the thermometer tube should be filled with transformer oil;
f. The dry type transformer shall be equipped with a temperature measuring device as specified by the manufacturer.
3.1.7 Transformers of 200O0kVA and above in unattended substations shall be equipped with remote monitoring devices for load current and top oil temperature. The oil-cooled transformer installed in the unattended substation shall have reliable measures to ensure that the temperature of the transformer does not exceed the specified value when the cooling system loses power, and is included in the site regulations.
3.2 Other requirements regarding transformer operation
3.2.1 Large and medium-sized transformers shall have temporary lifting bells and facilities and the required work space.
3.2.2 The installation of the pressure relief device shall ensure that the accidental fuel injection is unblocked and shall not be sprayed into the cable trench, busbar and other equipment, and shall be blocked if necessary.
3.2.3 The transformer shall have a nameplate with the running number and phase marking. The distribution transformers installed in the transformer room or on the platform and on the column should also be numbered and hung warning signs.
3.2.4 Under the operating conditions, the transformer should be able to safely check the oil conservator and casing oil level, top oil temperature, gas relay, and safe gas sampling, and if necessary, install a fixed ladder.
The transformer installed in the 3.2.5 room (hole) should have sufficient ventilation to avoid excessive transformer temperature. A transformer room equipped with mechanical ventilation should be capable of transmitting a remote signal when mechanical ventilation is stopped. The ventilation system of the transformer should generally not be in communication with other ventilation systems.
3.2.6 The door of the transformer room shall be made of flame retardant or non-combustible material and shall be locked. The name and operation number of the transformer should be marked on the door, and the “stop, high voltage danger” sign should be placed outside the door.
3.2.7 The place where the oil-immersed power transformer is installed shall be equipped with fire-fighting facilities and accident storage facilities in accordance with the relevant design regulations, and shall remain in good condition.
3.2.8 For transformers installed in areas with magnitudes of 7 and above, the following anti-seismic measures should be considered: a. Fixing the transformer chassis to the track;
b. When the transformer bushing is connected with the flexible conductor, it should be properly relaxed; when connecting with the hard conductor, the transitional soft connection should be lengthened appropriately;
c. When the cooler is arranged separately from the transformer, the transformer should be connected to the cooler via a valve, a flexible joint, and a connecting pipe;
d. The transformer shall be equipped with a shock-proof gas relay;
e. The chassis of the transformer on the column should be fixed to the bracket and the upper part should be fastened to the column. 3.2.9 When the apparent short-circuit apparent capacity of the system where the transformer is located is greater than the value specified in Table 2 of GB1094.5, measures to limit the short-circuit current shall be taken for the transformer in operation. The time for the transformer protection action should be less than the duration of the short-circuit heat resistance. 3.2.10 If an on-line monitoring device reflecting the insulation condition is installed on the transformer, the electrical signal shall be collected by the sensor and kept reliably grounded. The device for collecting dissolved gas in oil should have good sealing performance. 3.3 Technical documents
3.3.1 Before the transformer is put into operation, the construction unit shall hand over the following technical documents and drawings to the operating unit.
184.108.40.206 After the completion of the installation of the new equipment, it is required to pay:
a. Instructions, drawings and factory test reports provided by the manufacturer;
b. The connection test report of the main body, the cooling device and each accessory (casing, transformer, tap changer, gas relay, pressure relief valve and instrument, etc.) during installation, inspection and handling records during the lifting inspection of the body;
c. Record the whole process of installation (according to GBJ148 and relevant regulations of the manufacturer)
d. Transformer cooling system, control of the on-load voltage regulator and installation of the protection circuit;
e. Oil quality test and chromatographic analysis records;
f. A list of spare parts.
220.127.116.11 After the completion of the repair, it is required to pay:
a. The reasons for the maintenance of transformers and ancillary equipment and the whole process of inspection and maintenance;
b. Test record of transformers and ancillary equipment; c. Drying record of the transformer;
d. Oil quality test, chromatographic analysis and oil treatment record of the transformer.
3.3.2 Each transformer shall have a technical file of the following contents:
a. Transformer resume card;
b. All documents handed over after the completion of the installation;
c. Documents handed over after overhaul;
d. Preventive test record;
e. Calibration record for transformer protection and measuring devices;
f. Oil treatment and fueling records;
g.. Other test records and inspection records;
h. Record the transformer accident and abnormal operation (such as over temperature, gas relay action, outlet short circuit, severe over current, etc.).
3.3.3 When the transformer is handed over to the external unit, the technical file of the transformer must be handed over.
4.1 General operating conditions
4.1.1 The operating voltage of the transformer should generally not be higher than 105% of the rated voltage of the operating tap. For special use cases (for example, the active power of the transformer can flow in any direction), it is allowed to operate at a rated voltage of no more than 110%. There is no special requirement for the relationship between current and voltage. When the load current is the rated current K (K cluster 1) times, the voltage U is limited according to the following formula (1) The multiples and time of the overvoltage operation allowed by the shunt reactor, arc suppression coil, voltage regulator, etc., according to the manufacturer's specifications.
4.1.2 The non-excited voltage regulating transformer shall have the same rated capacity when it is changed to the tap position within the rated voltage of 5%. If it is a 7.5% and a 10% tap, its capacity is determined by the manufacturer; if there is no manufacturer's regulation, the capacity should be reduced by 2.5% and 5%. The capacity of each tapping position of the on-load tap changer is as specified by the manufacturer.
4.1.3 The top oil temperature of oil-immersed transformers should generally not exceed the requirements of Table 1 (manufacturers have regulations as specified by the manufacturer). When the temperature of the cooling medium is low, the top oil temperature also decreases accordingly. The top oil temperature of the Bairan Circulating Cooling Transformer should generally not exceed 85 °C.
Do a good job in the operation of the power transformer, so that we can reduce the occurrence of the wrong way in the use, so as to improve the efficiency of operation, and the use of principles in the later use.