Electricencyclopaedia: Know these electric cooling knowledge, you are in the eyes of others electrical expert!

Type of use of circuit breakers

Circuit breakers are classified into CAT A and CAT B. The following figure shows CAT A molded case circuit breaker.  CAT TYPE A circuit breaker is usually used as the incoming circuit breaker or terminal circuit breaker of the distribution cabinet. Generally, the MOLDED case circuit breaker is labeled CAT A.  Molded case circuit breakers are more common, careful friends should be able to notice.  

CAT B type circuit breaker is mainly used as a low-voltage line into the main switch, the general air circuit breaker for CAT B, generally installed in the distribution room distribution cabinet, we see less.

RCBO, RCCB and RCD are commonly used to describe the leakage protection function, but what is the difference between them?  

RCBO (Residual Current Operated Circuit-breaker with Integral Overcurrent Protection) refers to Residual Current Operated Circuit breakers that perform overload and/or short Circuit Protection.  Such as integrated leakage protection circuit breaker.  

RCCB (Residual Current Operated Circuit-breaker) refers to residual current action switches that cannot perform overload and/or short circuit protection, i.e. leakage switches.

RCD (Residual Current Devices) refers to residual current action protection devices, such as residual current action accessories, whose detection, judgment, and disconnection functions are independent of supply voltage.

What are surge protectors parameters 10/350 and 8/20?

These two parameters describe the lightning current curve waveform.  The two waveforms are both time and current curves. 10/350μs is the lightning current curve of typical lightning penetrating the earth, and the lightning current curve of lightning directly hitting the power line and lightning rod, which is generally called direct lightning wave shape.  

8/20μs is the electromagnetic pulse induced overvoltage caused by lightning breakdown of the earth, this induced overvoltage breakdown, burn equipment current curve, generally known as the induced lightning wave shape.  The current value of the surge protector is also based on the corresponding waveform.  

High voltage switchgear protection grade

Do you know what IP1X, IP2X, IP3X, IP4X, IP5X and IP6X protection classes stand for?  What is the primary protection of each level?  

Protection level refers to the protection degree of the shell, partition and other parts from the human body approaching live parts and touching moving parts and from external objects entering the internal equipment.  

IP1X protection against objects with a diameter greater than 50mm, mainly against solid objects with a diameter greater than 50mm and large areas of human body touching live parts in the cabinet.  

IP2X to protect objects with diameter greater than 12.5mm, mainly to protect solids with diameter greater than 12.5mm and live parts in the cabinet touched by hands.  

IP3X Protect objects with a diameter greater than 2.5mm, mainly the live parts of solid and metal wire cabinets with a diameter greater than 2.5mm.  

IP4X protects objects with a diameter greater than 1mm, mainly the live parts in the solid and metal wire cabinet with a diameter greater than 1mm.  

IP5X dustproof, mainly prevent dust from entering the shell, completely protect to touch the live parts in the cabinet.  

IP6X is the highest protection level of dust density, completely prevent dust and completely protect from touching live parts in the cabinet.  

Transformer in operation there will be "buzzing" sound how to solve?

Although it is noise, if it is not solved for a long time, it will certainly fail.  

It is mainly caused by the hysteresis expansion of iron chip in iron core (iron core with air gap and electromagnetic force). In addition, the electromagnetic force of winding and transmission of transformer related accessories (including resonance) can also cause noise.  

For on-site processing of transformer noise is too large, it is necessary to carefully analyze the source of sound, dry transformer usually by the body and shell resonance noise is more, a few cases are caused by abnormal loosening of fasteners noise.  

For both cases can be the scene of transformer various fasteners (screws, block, base Angle bolts, shell each connecting bolt, fall into the foreign body inside fan, centrifugal fan rotor swing, shell bottom bolt net off or loose bolts, etc.) to conduct a comprehensive inspection and retightened in place, to the resonance of parts for fastening or adding damping device (rubber), in order to reduce and eliminate the noise.