SINGLE PHASE THYRISTOR POWER REGULATOR.

Thread Starter

mnyakuzi

Joined Feb 4, 2016
2
hi all,
am trying to make a single phase thyristor power regulator for heating purposes which can accept a 4-20mA single from the plc and control the firing angle and hence control the power to the load and in my case electric heater. through a feedback from the temperature controller.
ive tried in vain to find a circuit for the same. any ideas will be highly appreciated.
 

Alec_t

Joined Sep 17, 2013
11,502
Welcome to AAC!
For heating control, burst mode (i.e whole cycle switching) would be better than phase-angle control in that it would produce less EMI.
What voltage/power rating does the heater have?
 

Thread Starter

mnyakuzi

Joined Feb 4, 2016
2
Welcome to AAC!
For heating control, burst mode (i.e whole cycle switching) would be better than phase-angle control in that it would produce less EMI.
What voltage/power rating does the heater have?
basically my project is plc controlled heating of electric furnace
trying to make a thyristor controller and use the 4-20mA for analogue control and also be able to record the temperature trends. making the controller has been an obstacle so far Since this is for project purposes,its only 500w heater,240v ac,50hz
 

crutschow

Joined Mar 14, 2008
25,247
Easiest is just to use a SSR (Solid-State-Relay) to control the heater using a burst-mode control as Alec_t said.
Use the control signal to adjust the duty-cycle controller to turn the power ON for several cycles and then OFF for a number of cycles.
The ON/OFF ratio determines the average power.
Can you program the PLC to generate this variable duty-cycle in response to the temperature?
 

ian field

Joined Oct 27, 2012
6,539
Easiest is just to use a SSR (Solid-State-Relay) to control the heater using a burst-mode control as Alec_t said.
Use the control signal to adjust the duty-cycle controller to turn the power ON for several cycles and then OFF for a number of cycles.
The ON/OFF ratio determines the average power.
Can you program the PLC to generate this variable duty-cycle in response to the temperature?
In that context; a zero crossing type SCR/triac opto-coupler driving the SCR would be better than a common or garden SSR.
 
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