CD Automation sales Manual
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CD Automation s.r.l.
CD Automation sales Manual
CD Automation s.r.l.
1. What is an SCR?
SCR is used in place of conventional AC power controllers made with
Variable Voltage controllers, or variable transformer and electromagnetic
contactor. SCR are typically used in electrothermal control applications of
various industries including temperature control for electric furnaces and
heat treatment processing.
2. The Principle behind SCR.
• There are two types of control
systems used in SCR. These are:
(1) Phase angle control
(2) Cycle control
• Phase angle control
As shown in Figure 1, under phase
angle control, power is supplied to
the load only during part of the
AC voltage waveform. Output
voltage can be controlled by
increasing or decreasing the
portion that is cut out.
CD Automation s.r.l.
• Cycle control
As shown in Figure 2, the power is supplied to the load for an ON
time and OFF Time during the cycle time. Adjusting the ON time is
possible to control the load power.
Other more sophisticated firing are available and will be treated
after.
CD Automation s.r.l.
3. Reason to use SCR?
1) SCR improve control precision. The degree of precision offered by SCR
as compared with a magnetic switch system is shown in Figure 3.
2) As solid-state devices, SCR provide increased reliability and longer life.
3) Maintenace is not necessary since there are no moving parts.
4) SCR produce no noise.
CD Automation s.r.l.
4. Applications
Tempering furnaces
Annealing furnaces and heat treatment
equipment
Molding equipment
Melting furnaces
Evacuated furnaces
Drying equipment
Heater Preheaters
Control
Baking ovens
Food-related equipment
Packaging and wrapping equipment
Road heaters
Defrosters
• Air conditioners
Agriculture and livestock industries
• Petrochemicals
Crystal growing equipment
Environmental test equipment
Vacuum tubes
CD Automation s.r.l.
5. Applications
Leading marks
Photo studios
Illumination
and Lighting Hotels and theaters
Planetariums
Fish gathering lights
Rectifiers
Power Induction lamps
Supply Crack detection equipment
Active charcoal manufacturing
equipment
Test and inspection
equipment
Particle accelerators
Magnetizing equipment
Motors Dc Motors
Torque motors
Vibrators
Miscellaneus Clutches
CD Automation s.r.l.
6. Specific Examples of Applications
Plastic Molding Equipment
Since injection machine used to make plastic products require the temperature of
all parts to be precisely controlled,many control zones are used. Therefore several
SCR to be used in a injection machine.
CD Automation s.r.l.
6. Specific Examples of Applications
Extruder
• Extruders are one of the best applications for thyristors units.
• In Italy we sell 24,000 units in this application.
• Coextrusion systems are everyday more and more used, we have done
systems with 120 zones.
• An important feature on CD Automation Thyristor units is the Heater
Break alarm.
• H.B. inside thyristor unit can be An important feature to overcome the non
availability of H.B. inside C460 MLC9000 module.
CD Automation s.r.l.
Chillers
• This application is tipical for plastic machinary.
• Actually in Italy is an important application for SCR units, CD3000S and
CD3000-2PH.
• In each chillers can be used from 1 to 4 heating zones.
CD Automation s.r.l.
Paint Drying Equipment
Paint drying equipment usually produces heat through infrared lamps. Usually
drying takes place in a tunnel containing a succession of drying lamps such that
it is necessary to independently control electric power at the tunnel entrance,
exit and points in between. Since temperature can be tightly controlled with
SCR product quality after drying treatment IS greatly improved.
This type of drying equipment is widely used for plant manufactured products
including cars and household applications.
CD Automation s.r.l.
Food Processing
There are many types of electric ovens used to bake such items as bread and
confectioneries, depending on the exact type of food involved and the level of
production necessary. There are ovens which have upper and lower heating
elements and “tunnel-type” ovens configured for mass production levels which
utilize a conveyor belt.
Figure 12 shows a tunnel-type oven. Each item can be consistently and evenly
baked through the use of SCR.
CD Automation s.r.l.
Melting Furnaces
Melting furnaces are electric furnaces meant for the melting and heat maintenance
of both metallic and non-metallic substances. One typical example of a melting
furnace for metals is the aluminium melting furnace used as one stage in die
casting and pressing equipment. Figure 13 shows aluminum die casting
equipment capable of melting aluminum ingots while maintaining a constant
internal temperature.
A heater is used to melt metals such as aluminum and certain alloys which have a
relatively low melting point. Substances which become conductive when melted,
such as glass, will themselves heat up if voltage is applied directly. A system
requiring heaters is said to use “indirect heating”, while a system depending on the
electrical resistivity of the substance being heated is said to use “direct heatig”
CD Automation s.r.l.
Ceramic Furnaces
The growing applications found for ceramics can be seen in everyday life. From
semiconductors to cars and ceramics products.
Since the temperatures required to bake such ceramics are extremely high from
1,500 to l,600°C, the heaters used in such furnaces are made with special materials
such as molybdenum.
Special firing and special feed back must be used. Application with special loads
will be treated during this training.
CD Automation s.r.l.
DC Power Sources
Figure 15 illustrates an example of a DC motor driven by an SCR combined
with a rectifier.
This cheap solution is used in amusement parks have built-in DC motors which
take DC voltage supply by the rail. The voltage required varies depending on
the number of cars running at the same time on rails. By using a feedback
control system are therefore commonly used for DC constant voltage control.
By using SCR in this way, it can be assured that all cars will run at a constant
speed.
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