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Several load control strategies for industrial furnace

Update time:2015-12-24 20:05:51Click times:2015
1, pure resistive load (cold and heat resistance change small load)
Can be taken to adjust the way as:
A, cycle (duty ratio control) or frequency over zero power technology and high power SSR overcome pressure mode power factor is low, the grid pollution shortcomings.
B, ordinary pressure regulating mode
C, zero SSR frequency over zero load current to the sine wave is uniform distribution, equipment operation and the total power of current relative balance (to avoid cycles on the control current mode), improve the uniformity of furnace temperature, avoid ammeter striker, is an important and improve the utilization rate of power supply and avoid electric power equipment capacity, node effect is very obvious
2, the silicon carbide (700 C: negative rent characteristics, namely the resistance value for negative temperature characteristic, 700 C positive temperature characteristic)
Phase shift control method can be used. Add slow start >10s, the maximum current limit, the output limit, can adjust the pressure, after the power transfer.
Should not be the zero mode of the full voltage starting, otherwise it will cause too large impact current, easy damage of controllable silicon and acceleration of silicon carbide aging. Generally use more than 1 minutes to slow start, to avoid the negative resistance near the shock current (more obvious) in the vicinity of 700 degrees. The step-down transformer, a silicon carbide rod in series or in the center of the ground can be individually adjusted each power and balance of silicon carbide aging control panel.
3, pure metal (carbon molybdenum rod, molybdenum wire, platinum and other R-T as a linear positive temperature characteristics):
Can adopt the way of phase shift of Buck transformer. Slow start >10s, maximum current limit, output limit, linear limit.
Although this kind of load changes of cold resistance, but resistance and temperature is linear relationship, through a step-down transformer, current limit and with multiple sets of PID and limiting the power of the instrument, the current limit of the design of low, medium and high temperature area.
4, transformer control:
Inductive load, the power on slow start gradually paramagnetic gentle off gradually closed magnetic field reduction; pulse width variable DC trigger technology, can provide enough reach thyristor engine in current lock time, avoid narrow pulse transformer trigger is not reliable.
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