E-JIN Heating System Co., Ltd.

※ Electric Current Control System ※

In general, the electric current control systems of electric furnace are described compressively

into 3 methods.

          1. SCR Control System

          2. ON/OFF Control System (MAGNETIC Control)

          3. SSR Control System

▣ SCR Control System Strong Points ▣

1) Describe SCR system easily, a table lamp(called Inverter stand) can be used by adjusting

   the brightness. If used 100% of electric power for stand lamp, one is dazzled with electric light.

   But if used 70%~80% of electric power, it is the right for eyes. You can reduce power

   consumption and protect your eyesight.

   In the example above, when electric furnace temperature rises at the first time, the furnace

   consumes 100% of electric power. Over time, SCR system can reach a preset temperature

   automatically just by using less than 100% of electric power. The electric power consumption

   rates(one of the SCR strong points) may differ slightly depending on electric furnaces. But it can 

   be operated by using 60%~70% of electric power and maintenance cost is low when operating.

2) In the explanation above, the problems about temperature difference will be resolved

   when it is operating.

3) It creates less ambient noise. (noise is created in cooling FAN to cool the radiator

   under SCR element)

▣ SCR Control System Weak Points ▣

1) First cost for Control Panel is more expensive than other control systems.

   (But you can save money because of lower maintenance costs after operating for one year

    or one and one-half years.)

2) SCR has a lower failure rate, but repairs must be carried out by experts in the event of a failure.

▣ ON/OFF Control System (MAGNETIC Control) Strong Points ▣

1) ON/OFF control system has quite a lower failure rate as compared with other control system.

   (But it needs to change, if the regular contact rates of magnetic switches are over by each

    manufacturer)

2) The parts supply and interchangeability are easy by manufacturer, so you can change by itself.

3) First cost for Control Panel is expensive.

▣ ON/OFF Control System (MAGNETIC Control) Weak Points ▣

1) It consumes an amount of electric power consumption. Describe easily, if it supplies 100% of

   electric power and 100% of electric power goes out like fluorescent light turns on and turns off,

   the electric power will be consumed than others. ON/OFF Control System is the same way.

   so the future maintenance costs will be expensive.

2) When the electric furnace temperatures rises or keep like explanation above, you need to take

   temperature difference into consideration as far as it goes, because it supplies 100% of electric

   power(more than the electricity requirement).

3) It makes a dull sound from panel box. (when the electromagnet sticks and comes off inside

   panel box, because ON/OFF control system is operated by MAGNETIC SWITCH)

▣ SSR Control System Strong Points ▣

1) First cost for Control Panel is expensive.

2) Control Panel for electric furnace can be organized in small.

3) It is quiet. (It is classified as a natural air cooling system and a forced air cooling system

   per SSR capacity. If the cooling fan is installed, it makes an operating sound)

4) To some degree, parts supply is easy. so you can change parts from by itself.

▣ SSR Control System Weak Points ▣

1) It consumes an amount of electric power consumption. It is similar to ON/OFF control system.

   In case of ON/OFF control system, the 100% of electric power is supplied and 100% of electric

   power goes out per 1 second. So the reaction time is a little slow. But SSR control system is

   a pulse control system. The reaction time(100% of electric power is supplied and goes out

   per 1 second) is sensitive. So it appears that it is similar to SCR control system, because current

   is not detected in ampere meter(because reaction time is sensitive). But it is desired that you

   would be better think it is similar to ON/OFF control system.

2) The temperature difference of electric furnace is inferior to SCR control system and it is superior

   to ON/OFF control system.

   But the difference exist on low temperature(below 400 degrees), and the difference is similar to

   SCR control system on middle-high temperature. (These has application to ‘Testing Furnace’ and

   ‘Compact Electric Furnace’)

   The above explanation is rudimentary brief descriptions. Even if there are some faults or

   the above is not correct, please read these explanations on the interpretative side of three

   control systems.