When we assemble a Proportional Power Control unit, energy savings are considerable since by working the voltage as a function of the analog signal (4–20 mA, 0-5/10Vdc) only the necessary power transmission is produced according to to the demand of the process.
With these control systems we avoid voltage peaks in the system and extend the life of the electrical resistances because the regulation is proportional and the expansion of the internal components is less.
What does a Proportional Power Control consist of?
To regulate power through thyristors, thyristor modules are used, which contain two SCRs connected in antiparallel. These Equipments can have single-phase, two-phase and three-phase connections, with control through O or phase angle.
SRC recommends phase angle control as it is the most accurate currently on the market.
When the SCR is fired at the beginning of the cycle (at approximately 0º), the module conducts approximately 360º and this causes maximum power transmission to the load. Instead, when the SCR is triggered near the positive peak, the module conducts 180º and this produces less power transmission to the load.
Through adjustments in the firing circuit, the activation of the SCRs can be delayed and, in this way, we have a variable transmission of power. Currently, one of the most widely used signals in industrial processes is the 4–20 mA signal, and control systems for thyristors use this signal to modulate power.
One of the most used applications in power control is to regulate temperature processes through electric heaters, for which a temperature controller with analog output, proportional power control and a temperature sensor are needed. With these components it is possible to obtain a proportional control of the power of the heating resistances, through the voltage modulation that the system performs. It is also possible to apply this system to ON-OFF type controls through a relay output in a temperature control.
SRC has single-phase and three-phase proportional power control equipment by phase angle for precise regulation of electrical heating resistors, considerably extending the life of the heaters, eliminating thermal shock and adjusting the electrical load for better energy management. Equipment from 20 to 500 Amps.