Model and parameter of dry type transformer_ Selection of dr

 

 

 

What is dry type transformer

 

Dry type transformer is widely used in local lighting, high-rise buildings, airports, docks, CNC mechanical equipment and other places. In short, dry type transformer refers to the transformer whose core and winding are not immersed in insulating oil. The cooling methods are divided into natural air cooling (an) and forced air cooling (AF). Under natural air cooling, the transformer can operate continuously for a long time under rated capacity. When forced air cooling, the output capacity of transformer can be increased by 50%. It is suitable for intermittent overload operation or emergency overload operation; because the load loss and impedance voltage increase greatly during overload, it is in non economic operation state, so it should not be in continuous overload operation for a long time.

 

 

 

Classification of dry type transformer

 

(1) Totally enclosed dry-type transformer: a transformer placed in a sealed enclosure without pressure and cooled by internal air circulation.

 

 

 

(2) Enclosed dry-type transformer: a transformer placed in a ventilated enclosure and cooled by external air circulation.

 

 

 

(3) Non enclosed dry-type transformer: transformer without protective enclosure, cooled by natural or forced air circulation.

 

 

 

Performance characteristics of dry type transformer

 

1. High safety: SG10 transformer has no combustible resin, can not support combustion in the process of use, can be flame retardant, will not explode and release toxic gases, will not cause harm to the environment, other equipment and human body, is not sensitive to humidity, dust and pollution; operation has no partial discharge and never "crack" possibility.

 

 

 

2. High reliability: both high and low voltage coils are made of Nomex insulating material, and impregnated with H-class solventless impregnating paint for many times by VPI vacuum pressure equipment, and cured by high temperature baking for many times. The product is grade H (180 ℃), and the main insulating material is grade C (220 ℃), with strong overload capacity and good short circuit resistance. Under the condition of good ventilation, 20% overload operation is allowed.

 

 

 

3. Energy saving and environmental protection: after the end of product life, steel, iron and other materials are easy to recycle; all Nomex Paper used will not release toxic substances when burning; other insulating materials can degrade and do not pollute the environment; the product has low loss, energy saving, low noise and flexible design.

 

 

 

 

1. From the insulation medium, it can be divided into SCB series epoxy resin cast dry-type transformer, and the insulation material is epoxy resin. SGB series H class insulated non encapsulated dry-type transformer, insulation material is nomac paper DuPont paint.

 

 

 

2. From the core material: silicon steel core dry-type transformer SCB, SGB series. Amorphous alloy core series dry type transformers: scbh, SGB series.

 

 

 

3. The energy saving sequence is divided into scb9, scb10, scb11, scb13, scbh15, sgb9, SGB10, sgb11, sgb13, sgbh15 series, etc.

 

 

 

Product solution of dry type transformer: for example, (scb10-1000kva/0kv/0.4kv): s means that the transformer is a three-phase transformer, and if s is replaced with D, it means that the transformer is single-phase. C means that the winding of this transformer is resin cast solid. B means foil winding, or winding winding if R is l, aluminum winding if l, and on load voltage regulation (copper is not standard). The meaning of 10 is the design serial number, also called the technical serial number. 1000KVA is the rated capacity of the transformer (1000 kVA). 10kV means primary rated voltage, 0.4kV means secondary rated voltage.

 

 

 

The alphabetical order and meaning of the product model of dry type transformer

 

1. Winding coupling mode, meaning: * * (not standard); self coupling (O means).

 

 

 

2. Phase number, meaning: single phase (d); three phase (s).

 

 

 

3. The insulation medium outside winding has the following meanings: transformer oil (non-standard); air (g): gas (q); molded solid pouring type (c): wrapped type (CR): flammable liquid (R).

 

 

 

4. The type and meaning of cooling device are divided into natural circulation cooling device (not standard): air cooler (f): water cooler (s).

 

 

 

5. Oil circulation mode, meaning: natural circulation (not standard); forced oil circulation (P).

 

 

 

6. Winding number, meaning division; double winding (non standard); three winding (s); double split winding (f).

 

 

 

7. Voltage regulation mode, meaning division; excitation free voltage regulation (nonstandard): on load regulation and suppression (z).

 

 

 

8. Coil conductor material, meaning: copper (not standard); copper foil (b); aluminum (L) aluminum foil (LB).

 

 

 

9. Core material, meaning; electrical steel sheet (not standard); amorphous alloy (H).

 

 

 

10. Special purpose or special structure, meaning division; sealed type (m); series use (c); starting and using (q); lightning protection (b); capacity regulating (T); high impedance (k) traction (QY); low noise (z); cable outgoing (L); isolation (G); electric capacity compensation (RB); power lighting (y); auxiliary transformer (CY); full insulation (J) ; for excitation of synchronous motor (LC).

 

The transformer is selected according to the nature of the load

 

 

 

1) When there are a large number of primary or secondary loads, two or more transformers should be installed. When one of them is disconnected, the capacity of other transformers can meet the power consumption of primary and secondary loads. 1、 The secondary load should be concentrated as far as possible and should not be too scattered.

 

 

 

2) When the seasonal load capacity is large, special transformer should be installed. For example, the load of air-conditioning chiller and heating electric load in large civil s4270d27-29 27 2005.7.29, 3:24 am buildings.

 

 

 

3) When the concentrated load is large, special transformer should be installed. Such as large heating equipment, large X-ray machine, electric arc furnace, etc.

 

 

 

4) When the lighting load is large or the power and lighting use a common transformer, which seriously affects the lighting quality and bulb life, the lighting special transformer can be set. Generally, power and lighting share the same transformer.

 

 

 

Choose the transformer according to the use environment:

 

 

 

1) Under normal medium conditions, oil immersed transformer or dry-type transformer can be selected, such as independent or attached substation of industrial and mining enterprises, agriculture, independent substation of residential area, etc. The optional transformers are S8, S9, S10, SC (b) 9, SC (b) 10, etc.

 

 

 

2) In multi-storey or high-rise buildings, non combustible or non combustible transformers should be selected, such as SC (b) 9, SC (b) 10, SCZ (b) 9, SCZ (b) 10, etc.

 

 

 

3) In places where dust or corrosive gas seriously affect the safe operation of transformers, closed or sealed transformers should be selected, such as BS 9, S9 -, S10 -, sh12-m, etc.

 

 

 

4) High and low power distribution devices without combustible oil and non oil immersed distribution transformers can be set in the same room. At this time, the transformer should be equipped with IP2X protective enclosure for safety.

 

 

 

The transformer is selected according to the power load

 

 

 

1) For the capacity of distribution transformer, the capacity of facilities of various electrical equipment should be integrated to calculate the calculated load (generally excluding fire load). The apparent capacity after compensation is the basis for selecting the capacity and number of transformers. Generally, the load rate of transformer is about 85%. This method is simple and can be used to estimate capacity.

 

 

 

2) In GB / t17468-1998 guide for selection of power transformers, the recommended capacity selection of distribution transformers should be determined according to GB / t17211-1998 guide for load of dry type power transformers and calculated load. The above two guidelines provide computer program and normal cycle load diagram to determine the capacity of distribution transformer.