supplyCalcium carbide furnace transformer

Calcium carbide furnace smelting is an important branch of submerged arc furnace smelting. As the power supply equipment of calcium carbide furnace, calcium carbide furnace transformer is a very important equipment in the system of calcium carbide furnace. As the leading manufacturer of electric furnace transformers in China and the leading drafting enterprise of all national standards for electric furnace transformers, our company has been committed to the design and development of calcium carbide furnace transformers and technological innovation. Among them, calcium carbide furnace transformer has experienced the whole process of development from scratch, from small to large, and according to the development of calcium carbide furnace transformer technology, constantly revised and improved calcium carbide furnace transformer standards, including "submerged arc furnace transformer General Rules", "calcium carbide furnace transformer Technical parameters and requirements" and so on.

The design and development level of our company's calcium carbide furnace transformer has been at the leading level in China. It has successively been Inner Mongolia Baiyanhu Chemical (HCSFPZ-2000/35), Yibin Tianyuan Group (HCSSPZ-2000/110), Ningxia Zhongwei Mingji (HCSSPZ-16500/110), Inner Mongolia Lier Chemical (HCSFPZ-18000/110), Wuhai Haixin Chemical (HCSFPZ-) 27500/35), Zhongyan Jilantai (HCDSPZ-9000/35), Pingshan Coal Industry (HCDSPZ-10000/110), Inner Mongolia Yidong (HCDSPZ-13500/110), Shanxi Yangmei (HCDFPZ-13500/110), Jinchang Cement (HCDSPZ-18000/ 110), Ordos City Junzheng (HCDSPZ-27000/35) and other enterprises supplied calcium carbide furnace transformers. Since 1990, our company has provided 1100 sets of calcium carbide furnace transformers for domestic and foreign users, of which more than 300 three-phase calcium carbide furnace transformers and more than 800 single-phase calcium carbide furnace transformers. Based on the production of a large number of calcium carbide furnace transformer products, and according to the continuous progress of calcium carbide furnace transformer requirements, the standard is revised and improved. At present, our company has formed 10kV, 35kV, 66kV, 110kV each voltage level of perfect calcium carbide furnace transformer manufacturing technology, process means and inspection specifications.

As a kind of submerged arc furnace transformer, calcium carbide furnace transformer is characterized by small secondary output voltage and large secondary output current, so the power factor of calcium carbide furnace system is generally not high. At the same time, the system load is relatively stable, requiring the calcium carbide furnace transformer impedance is small, far lower than the power transformer of the same voltage level, in order to improve the efficiency of the system. The above characteristics cause the failure of the calcium carbide furnace system, such as external short circuit, which will cause immeasurable damage to the calcium carbide furnace transformer. Therefore, high requirements are put forward for the design calculation, structure form, production process and test of calcium carbide furnace transformer.

In order to improve the power factor of calcium carbide furnace system, calcium carbide furnace transformer adopts a single compensation winding, that is, a way with three times compensation winding is an economic way of system operation, but due to structural reasons, the compensation winding of calcium carbide furnace transformer is relatively weak to withstand short circuit. In order to improve the ability of calcium carbide furnace transformer to withstand short circuit, our company in the design of calcium carbide furnace transformer, through the introduction of professional electromagnetic field, dynamic short-circuit mechanical force simulation verification software for verification and calculation, so that the compensation winding has a sufficient safety factor to ensure that the calcium carbide furnace transformer to withstand short circuit capacity. At the same time, in order to improve the ability of compensation windings to withstand overvoltage, the design calculation is carried out according to the improvement of the insulation level of compensation windings. For example, the voltage level of conventional compensation windings is mostly 10kV, and our company designs and calculates it according to 20kV, and verifies and analyzes it through wave process software to ensure the overvoltage ability of compensation windings.

When the capacitor compensation of the calcium carbide furnace transformer adopts series compensation, the auxiliary variable core flux density and winding current density are designed and calculated according to the compensated parameters, and sufficient margin is retained to make the overload capacity of the calcium carbide furnace transformer strong.

Our company also undertakes low-voltage shunt compensation transformer, according to the working condition of calcium carbide furnace, to ensure that the compensation transformer does not appear overexcitation, and can adjust the working voltage of the reactor to ensure the efficiency of the capacitor.

Our company in the calcium carbide furnace transformer technology innovation at the same time, summed up and applied the following patented technology: Electric furnace transformer "8" shape low voltage winding parallel connection structure (ZL 2010 2 0510480.3), electric furnace transformer low voltage cold pressure connection structure (ZL 2011 2 0197865.3), electric furnace transformer control cable bridge (ZL 2012 2 0174554.X), a single-phase electric furnace transformer structure (ZL 2012 2 0174582.1, the structure is the load regulator switch placed on the high voltage side, convenient for the on-site transformer installation work).

This manual is applicable to the buried power transformer produced by our company, the capacity is less than 1000kVA, the voltage level is 10kV and below, and the rated frequency is 50Hz. After the normal transportation of the transformer of this series of products, there is no need to carry out the core inspection, you can assemble the relevant parts for loading and unloading, do the acceptance test project, and then put into operation.

1. Product overview

A buried transformer is a compact power distribution facility in which transformers are installed in the same tank.

The components such as non-exciting tap-changer and low-voltage outlet bushing are arranged in the part of the box. The high voltage inlet line uses a fully insulated, fully sealed elbow type cable joint. The high voltage cable inlet elbow type cable connector can be used as side outlet or part outlet according to the size of the installation site.

Buried transformers can be installed in basements (cellars) and highway tunnels. The box shell is made of stainless steel or similar materials. High and low voltage inlet and outlet cables are waterproof, fully sealed, fully insulated, and fully shielded. They do not occupy ground space, can be submerged in water for a certain period of time, and are maintenance-free. It can ensure the perfect unity of power supply facilities and the surrounding environment, and can be widely used in densely populated central urban areas and streets, highways, Bridges, tunnels, parking lots, airports, ports, tourist attractions and other lighting systems, especially for users who have strict requirements on height and floor area. In product design, fully consider the special situation of ventilation and heat dissipation, the use of low loss and low temperature rise design, easy to operate, reliable operation.

2. Product implementation standards

2.1 GB1094.1.2-1996 "Power Transformer"

2.2 GB1094.3.5-2003 "Power Transformer"

2.3GB /T6451-1999 "Three-phase oil-immersed power transformer technical parameters and requirements"

2.4GB /T15164-1994 "Load Guidelines for Oil-immersed Power Transformers"

2.5JB/T10544-2006 "Underground Transformer"

3. Conditions of use

3.1 Current and voltage waveform: sine wave or approximate sine wave;

3.2 Three-phase current and voltage: roughly symmetrical;

3.3 Installation environment: Level 4 pollution;

3.4 High temperature: +50℃;

3.5 Low temperature: -25℃;

3.6 Average daily temperature: +30℃;

3.7 Average annual temperature: +20℃;

3.8 Altitude: ≤1000m;

3.9 Operating Environment: Underground

3. Special conditions of use:

Any special conditions of use that need to meet the normal conditions of use should be explained at the time of inquiry and order.

Step 4 Transport

4.1 The transportation method of the transformer to the installation site is mainly road or rail transportation. Such transformers are all full of oil transport, should be attached with accessories, factory technical documents, etc., packed into a separate box and shipped together with the transformer.

4.2 When lifting the transformer, the transformer with the folding edge of the box cover shall be lifted by the hanging plate on the box cover, which can fully bear the total weight of the transformer. It is strictly forbidden to use the hanging plate on the wall of the tank box to lift the total weight of the transformer with the folding edge of the box cover. The hanging plate on the wall of the tank box is only used for transportation and binding. Other structural transformers, lid lifting plates and fuel tank lifting plates can be used. When lifting, the Angle between the rope and the vertical line is less than 30°. If this requirement cannot be met due to the lifting height limit, the lifting beam should be used.

2.3 The inclination of the transformer shall not exceed 15° during transportation, and it shall be protected from shock and vibration.

5. Acceptance and testing

5.1 Check whether all packing cases and boxes are in good condition.

5.2 Check whether the data of the transformer nameplate conforms to the order contract, and check whether the factory technical documents are complete.

5.2 Check whether the transformer shape is intact, whether there are parts defects and oil leaks.

5.3 After the inspection, the transformer shall be tested before installation according to GB50150-91 "Handover Test Standard".

6. Check and accept

After receiving the transformer, the user should check it immediately.

6.1 Check whether the nameplate data of the product is consistent with the order contract, such as product model, rated capacity, rated voltage, connection group label, impedance voltage, etc.

6.2 Checking whether the delivery documents are complete.

6.3 Check whether the components in the packing case are consistent with the packing list.

6.4 Check whether the transformer is damaged during transportation, whether the parts of the transformer are damaged or displaced, whether the wiring is loose or broken, whether the insulation is damaged, whether there is dirt or foreign matter. At the same time, if there are cushion posts used in transportation, they must be removed.

6.5 If the product is not put into operation immediately after the inspection is completed, it must be repackaged and placed in a safe and dry place in the room to prevent damage and theft.

7. Storage and storage

7.1 The packaging of products that need storage shall not be removed, and the packaging shall be restored after acceptance.

7.2 Products that need long-term storage must be stored in the warehouse, which should be clean and dry, and should not store active chemicals and corrosive substances at the same time.

7.3 Stacking is not allowed for all products.

7.4 Products placed outdoors for a short period of time should be padded with wooden squares, with a height of not less than 100mm.

8. Installation and commissioning

8.1 Lift the transformer with a lifting device into the prefabricated pit, secure the transformer shell with anchor bolts, and effectively ground the transformer shell. There is appropriate space around the transformer to set up drainage facilities, and its cover should be set up ventilation holes and manholes to facilitate heat dissipation and monitoring operation.

8.2 Installation of High Voltage Cables

8.2.1 The connection between the high voltage cable and the toggle cable plug must be performed by professionally trained cable operators. For the connection procedure, see the corresponding cable instruction manual.

8.2.2 Before installing the toggle cable plug, it must be kept clean at all times to avoid dust and dirt. Note: The external insulating surface of the tapered end of the HV bushing and the internal insulating surface of the toggle cable plug cannot be touched by hand. Clean with a special clean cloth, and then evenly coated with a layer of silicone grease, ready for assembly.

8.2.3 The toggle cable plug should be inserted and removed in the case of power failure.

8.3 Installation of Low-voltage Cables

8.3.1 Wipe all parts with a clean cloth (paper) before installation. Insert the connector with the terminal crimped into the connector, tighten the stud on the sleeve to ensure that the connector is inserted in place, and insert the connector with the cable into the sleeve coated with silicone grease. Note: Each component must ensure that the horizontal and vertical alignment, the rear plug cover and the M10 end of the stud must be aligned, the upper two buttons feel no abnormal before continuing to tighten, but do not overforce (ensure that the seal does not leak), otherwise it will cause chaos, loose affect the electrical performance, resulting in unnecessary accidents. Silicone grease must be spread evenly, with no omissions.

8.3.2 After the low-voltage elbow cable is connected, secure the nuts to the stud bolts with a fastening force of 45kg±2kg using a special socket wrench, tighten the rear plug cover to the stud to ensure proper coordination and prevent creepage caused by air leakage, and put on the rear protective cap.

8.4 Tap-changer Operations

The operating handle of the non-exciting tap-changer is sealed with a shield. After confirming the power failure, open the protective cover and adjust the switch. After the operation is complete, carefully seal the cover, and tighten the sealing torque to 10N.m.

8.5 Operation of high-voltage fuses

8.5.1 The high-voltage fuse is used to fuse the transformer immediately when the internal fault occurs, and as a backup protection when the low-voltage outlet side has a phase or multiphase fault, to prevent the expansion of the fault range and play a protective role.

Step 9 Run

9.1 Before putting into operation, check whether the transformer oil tank, elbow cable head, high voltage cable shielding line, etc. are reliably grounded; Check whether the lock device of the pressure relief valve has been removed; Ensure that fasteners are not loose.

9.2 Operate according to relevant transformer operation rules stipulated by the state.

10. Buried transformer inspection, inspection and maintenance

10.1 Main Contents of inspection

10.1.1 Check the underground transformer for abnormal sound

10.1.2 Check whether the underground transformer high voltage cable joint leaks oil

10.1.3 Check whether the oil temperature, oil color, oil surface is normal, there is no abnormal sound, odor;

10.1.4 Use an infrared thermometer to measure whether the surface temperature of the buried transformer high voltage cable joint is abnormal

10.1.5 Whether the high-voltage cable connector is clean and has traces of deformation, damage, and discharge

10.1.6 Check each electrical connection point for corrosion, overheating and burning;

10.1.7 Checking the ground transformer grounding Device

a) Whether the ground lead is lost, broken or damaged;

b) Whether the joint contact is good, whether the bolt is loose and corroded;

c) Whether the grounding body is exposed or seriously corroded.

10.1.8 Check the shell for paint removal and rust; Whether the welding joint has cracks and oil seepage; Whether the ground is well grounded;

10.1.9 Check whether the sealing gaskets of each part are aging, cracking, and whether the cracks are leaking oil;

10.1.10 Check whether the bolts are complete and loose;

10.1.11 Check whether the nameplate and other marks are in good condition;

10.1.12 Check whether the insulation resistance is normal.

10.1.13 Check the tightness of the low-voltage junction box, fuse box, tap-changer cover and other sealing components on the transformer cover.

Table 1 Periodic table of inspection, inspection and maintenance of buried transformers

Serial number	entry	cycle	Reserve injection
1	Regular inspection	quarterly
2	Clean high voltage cable joints and check fuses	Usually once a year	The number of dirty areas should be increased appropriately
3	Insulation resistance measurement	Once a year
4	Oil withstand pressure, water test	At least once every five years

10.2 The buried transformer should be inspected and treated in any of the following cases.

a) High voltage cable joint overheating, breakdown, burning, serious pollution;

b) oil leakage, serious oil seepage, oil level can not be seen on the oil label;

c) Aging insulation oil, oil color significantly darker;

d) Most of the shell and radiator paint, serious rust;

e) Abnormal sound, discharge sound, smoke, oil injection and overheating phenomenon;

f) If the transformer is immersed in water for some reason, it should be cleaned before re-transmitting power, check whether the insulation is qualified, and confirm that it meets the requirements for transmitting power before transmitting power.

10.3 Maintenance of the buried transformer

The buried transformer used in the highway tunnel should be inspected and treated if the situation described in 10.2 occurs.

10.3.1 Replacement of High voltage Fuse (if any)

If the high voltage fuse is in the case of internal fault of the transformer, it can be replaced after the fault is removed. The specific steps are as follows:

a. Strictly implement the safety operation procedures of the power system, and use qualified operating tools and clothing that meet the safety requirements.

b. Cut off the power supply on the power supply side of the substation, and hang up the grounding device and warning sign.

c. Check whether the external grounding of the fuel tank is reliable.

d. Pull the pull ring of the pressure release valve to release pressure.

e. Open the fuse cover and replace the fuse. After replacement, measure the resistance and insulation resistance of the high and low voltage side windings of the transformer to ensure that the transformer is not faulty before resuming the operation and supplying power.

f. In the above operations, all opened seals should be replaced by seals, and re-sealed according to installation requirements. The tightening force of all seals is 10N.m

10.3.2 The high voltage side of the buried transformer in the expressway tunnel is a hand-in-hand structure. In order to shorten the power outage caused by the maintenance of the transformer, the transformer should be moved out of the transformer room for maintenance and processing, and the high voltage connection box should be temporarily moved into the transformer room for temporary connection, and replaced after the transformer is repaired.

10.3.3 If the buried transformer fails, the manufacturer should be notified to send professional maintenance personnel.

Appendix A

(Normative Appendix)

Transformer test standard

A1 insulation resistance measurement

Use a meter with a rated voltage of 1000 ~ 2500V for measurement, and its value is not less than 70% of the factory value (Table B1 is a comparison after conversion to the same temperature).

Table B1 insulation resistance conversion coefficient

Temperature (℃)	5	10	15	20	25	30	35	40	45
Conversion factor	1.2	1.5	1.8	2.3	2.8	3.4	4.1	5.3	7.6

Transformer insulation resistance measurement should be carried out in dry weather above 5 ° C (humidity does not exceed 75%), disconnect other facilities, wipe the sleeve, measure the temperature of the transformer, insulation resistance value should not be lower than the provisions of Table B2.

A2 power frequency withstand voltage test

a) When the insulation resistance value is lower than the allowable value, the voltage test shall not be carried out;

b) The new product and the overhauled transformer pass the test according to the values specified in Table A2.

Table A2 Allowable insulation resistance of transformer (MΩ)

Temperature ° C Measurement item	10	20	30	40	50	60	70	80
Once to twice to the ground	450	300	200	130	90	60	40	25
Secondary ground	450	300	200	130	90	60	40	25

Table A3 power frequency withstand voltage test value

Voltage level (kV)	High voltage side (kV)		Low voltage side (kV)		Test time (minutes)
	New product	After overhaul	New product	After overhaul
10	35	30	5	4	1
6	25	21	5	4	1

Note: Run non-standard transformer, if you need to work frequency voltage test, can be carried out according to the specified value after overhaul.

A3 DC resistance test

a) Check whether the tap position of the transformer is normal and whether the circuit is well connected;

b) The unbalance of the DC resistance between the three phase lines is not more than 2% according to the following formula.