change-over switch

change-over switch

 

Crucible change switch or change-over switch is an apparatus for changing the crucible connected to furnace feeder. In fact, the switch changes the power flow from one crucible to the other one.

Chang-over switch is essential for induction furnaces. Without switch turning on and off and changing power flow between crucibles will be disturbing and time-consuming. Also operation reliability and protection of the furnace would not be reasonable.

Although change-over switch design can be in a way that is capable of connecting several feeders and crucibles, but generally it is designed for connecting a feeder to 2 crucibles.

Change-over switches are categorized in 3 types according to their operation mechanism:

Manual, Electrical and pnumatical

• Manual: In this type of change-over switches, the switching process is handled manually through a bar connected to the switch.
• Electrical: In this type of change-over switches, the switching process is handled by an electro motor’s force.
• Pnumatical: In this type of change-over switches, the switching process is handled using pneumatic cylinder taking orders from control section. This type is most common one in the steel industry.

As mentioned above, the pneumatica change-over switch is the most common one amongst others and is more reliable. Hence, this type of change-over switches is the customary product of Araz Trans company. In the upcoming, the produced change-over switches are discussed.

Our pneumatic change-over switches are designed for normal and high-power applications, both having up to 3000 V isolation capability and only the current ratings are different. Every contact of the normal switch can bear up to 10000 A, while it is 12000 A for the high-power switch. It should be noted that contacts can bear 120% of their nominal current, ultimately and up to 150% of their nominal current, instantaneously.

Below illustrations show apllication of normal and high-power change-over switches (made by Araz Trans Co.) For both normal and high current crucibles, respectively:

It is noteworthy that all our change-over switch products are equipped with their own control box containing interlock circuits and sensors to avoid unplanned conditions of the pneumatic cylinders, uplifting the reliability.