Pre-installed American Box Transformer

Model and meaning

● Environmental Conditions of Use

◆ Environment temperature : The Pre-installed American Box Transformer should be use in the environment between -30~40℃

◆ Altitude : Below 4000m

◆ Wind speed : Below 34m/s

◆ Humidity : The average daily relative humidity is not more than 95%; The monthly relative humidity value is not more than 95%

◆ Shockproof level :The horizontal acceleration is not more than 0.4m/S², and the vertical acceleration is not more than 0.15m/S²

◆ Installation inclination : Within 3°

◆ Installation environment :The surrounding air is not obviously polluted by corrosive and combustible gases, and there is no violent vibration at the installation site.

Note :When ordering Pre-installed American Box Transformer beyond the above conditions, you can negotiate with our company.

● Technical Parameter Table

◆ Transformer

◆ Load Switch

The load switch of Pre-installed American Box Transformer is oil-immersed, three-phase linkage switch and spring operating mechanism; It can be opened and closed with load, and its opening and closing speed has nothing to do with the operating force. The types are two-station, four-station T-type and four-station V-type.

◆ Backup Protection Fuse

The fuse of Pre-installed American Box Transformer is connected in series with the plug-in fuse in the transformer branch (see R1 and R2 in Figure 2) to form a full-range protection fuse. It only blows when there is a short-circuit fault inside the transformer, so the probability of blowing is very low. It is installed in the upper oil tank, and the oil tank needs to be opened if it is to be updated.

◆ Plug In Fuse

1.The Fuse’ core of Pre-installed American Box Transformer has two characteristics of temperature and current, that is, overload occurs at the load end, or it melts when the temperature is too high. Plug-in fuse and backup protection fuse are used in series, which can protect the whole range from several amperes to several thousand amperes, and the maximum breaking current is 50kA.

2.The reasonable matching of backup fuse and plug-in fuse will directly affect the performance of the whole transformer. See the following table for a part of the fuse selection guidelines in 10kV Pre-installed American Box Transformer for reference.

3.Plug-in fuse is an element that can replace the fuse core externally. When replacing, first pull the pull ring of the pressure relief valve of the upper fuel tank to balance the pressure inside and outside the fuel tank. In order to ensure the safety of operators and equipment, plug-in fuses should be plugged and unplugged when there is no load. Therefore, the low-voltage switch should be turned off first to cut off the full load on the low-voltage side. Then, the handle on the fuse seat should be unscrewed with the operating handle, and then rotated by about 90 degrees to eliminate the adhesion between the gasket and the outer wall. The fuse melt should be pulled obliquely upward for 70-80mm, and it should stay for a few seconds. After some oil on the melt is drained, the melt should be pulled out to avoid oil droplets from other components outside the fuel tank. Wipe the surface of the melt with a clean cotton cloth, and then replace the core. When replacing, be sure to pay attention to the parameters indicated on the molten core, and different parameters cannot be substituted. See Attachment 3 for replacement steps. Insert the molten core after replacement into the fuse support, and when the handle on the molten core is turned to the locking position, ensure that the stainless steel washer is close to the fuse support, and the handle is buckled on the boss to ensure that the substation is completely sealed and free from moisture. Then, the low-voltage switch is closed again, and the power supply can be resumed at this time.

4.Because the Pre-installed American Box Transformer is a three-phase system, whether it is a backup protection fuse or a plug-in fuse, when one-phase melt melts, the three-phase melt should be replaced generally, unless it can be determined that only one-phase melt has passed the fault current.