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Ref: Thyristors SRF.ppt (11/06/2014) EUROTHERM CONTROLS a bc Why Thyristor Power Control Units Rather Than Contactors? l Better Temperature Control - Deliver.

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Presentation on theme: "Ref: Thyristors SRF.ppt (11/06/2014) EUROTHERM CONTROLS a bc Why Thyristor Power Control Units Rather Than Contactors? l Better Temperature Control - Deliver."— Presentation transcript:

1 Ref: Thyristors SRF.ppt (11/06/2014) EUROTHERM CONTROLS a bc Why Thyristor Power Control Units Rather Than Contactors? l Better Temperature Control - Deliver short bursts to match power demand l Eliminates Temperature Fluctuations - Sense changes in supply and adjust power delivery to prevent power fluctuations l Increased Production - built in diagnostics and partial load failure detection allow preventative maintenance before total failure and costly shut downs of process l Lower Maintenance Costs - no moving parts and plug in design increases heating element Lifetime - reduced thermo- mechanical stress l Process Protection - Current and Power limits protects process and heating elements l Lower Energy Costs - Allows plant wide energy monitoring which reduces peak demand

2 Ref: P.ppt (11/06/2014) 2 EUROTHERM CONTROLS a bc Thyristor Power Control Will only conduct one way Firing Circuit Parallel Pairs AnodeCathode Gate Thyristor Device

3 Ref: Thyristors SRF.ppt (11/06/2014) EUROTHERM CONTROLS a bc Protection Snubber - Resistor/ Capacitor for elimination of spikes and false triggering particularly on transformer loads. Fuse MOV Snubber Firing Circuit Isolation Eurotherm Thyristor Unit Control Circuit MOV - Metal Oxide Varistor - Resistance changes on voltage, as voltage rises mainly on spikes it will absorb the excess voltage Fuse - Protecting against over current draw, will blow faster than the thyristor operates.

4 Ref: Thyristors SRF.ppt (11/06/2014) EUROTHERM CONTROLS a bc Firing Modes Logic Burst / Whole Cycle Single Cycle Phase Angle

5 Ref: Thyristors SRF.ppt (11/06/2014) EUROTHERM CONTROLS a bc Logic Firing - Logic Input On at Voltage zero. Off at Current zero. Logic O/P from controller Typically Off 5Vdc To minimise interference the thyristor unit switches on at the first zero crossing of the mains voltage after the the logic input goes On

6 Ref: Thyristors SRF.ppt (11/06/2014) EUROTHERM CONTROLS a bc Whole Cycle Firing/Burst Firing - Analog I/P Cycle Time giving for 50% output At 50% T ON = T OFF T CYCLE = T ON + T OFF CYCLE T ON T OFF T For lesser disturbance on mains you may increase the cycle time Typical 1 cycle to 256 cycles approx 5 secs Long cycle time can be few mins

7 Ref: Thyristors SRF.ppt (11/06/2014) EUROTHERM CONTROLS a bc Single Cycle Firing - Analog I/P Cycle Time is 2 cycles at 50% 50% Power 33% Power T T CYCLE Silicon carbide When element new the resistance is low and full voltage must only be applied for short bursts. As the elements heat up and or age the voltage can be sustained for longer periods. To prevent problems on new elements a power limiting must be used otherwise the element can shatter

8 Ref: P.ppt (11/06/2014) 8 EUROTHERM CONTROLS a bc TE 200, TC2000 & TC2001 3 Wire Star 3 Wire Delta TC2000, TE200 or TC2001 TC2000, TE200 or TC2001 Less Expensive than three leg control but when the unit is off the non-controlled leg is at line potential

9 Ref: Thyristors SRF.ppt (11/06/2014) EUROTHERM CONTROLS a bc Phase Angle - Analog I/P Firing equally delayed for each 1/2 cycle Shown as 50% Not widely used in Europe as there are problems with CE requirements. On

10 Ref: Thyristors SRF.ppt (11/06/2014) EUROTHERM CONTROLS a bc Load Types Fixed Resistance - Any firing mode Variable Resistance - Current limit or single cycle Transformer Coupled - Phase angle or burst firing with delayed start. This reduces surge currents. Will switch on at zero crossing point of current. Inductive as above

11 Ref: P.ppt (11/06/2014) 11 EUROTHERM CONTROLS a bc Load Types

12 Ref: P.ppt (11/06/2014) 12 EUROTHERM CONTROLS a bc Single Phase - Constant Load Resistance SSDS / RSDATE 10S TC1027425S / 450

13 Ref: P.ppt (11/06/2014) 13 EUROTHERM CONTROLS a bc Single Phase - Variable Load Resistance TE10A 425A460 TC1028

14 Ref: P.ppt (11/06/2014) 14 EUROTHERM CONTROLS a bc Three Phase - Constant Load Resistance RS3DA / RS3AA TE200S / TE200A TC2000 TC2001 TC3000 TC300

15 Ref: P.ppt (11/06/2014) 15 EUROTHERM CONTROLS a bc Three Phase - Variable Load Resistance TC2001 TC3001

16 Ref: Thyristors SRF.ppt (11/06/2014) EUROTHERM CONTROLS a bc Continental SSDARSDARS3DA

17 Ref: Thyristors SRF.ppt (11/06/2014) EUROTHERM CONTROLS a bc TU Series

18 Ref: Thyristors SRF.ppt (11/06/2014) EUROTHERM CONTROLS a bc TC Series

19 Ref: Thyristors SRF.ppt (11/06/2014) EUROTHERM CONTROLS a bc TE10S / TE10A

20 Ref: Thyristors SRF.ppt (11/06/2014) EUROTHERM CONTROLS a bc 450 / 460

21 Ref: Thyristors SRF.ppt (11/06/2014) EUROTHERM CONTROLS a bc 425S / 425A


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