Mutiple parallel control system. A professional temperature control system is developed on liquid zinc temperature and extend the lifetime of heating elements, widely affirmed by our customers, which improve the temperature control effectively. Temperatre control instrument adjusts CU (control unit) output signal automatically according the feedback signal of thermometric component. UC adjusts output voltage of silicon controlled rectifier (SCR) according to the monitoring signal, non-contact, non-impact, non-overshoot. Double control system for manual/auto is adopted to improve the control precision and to reduce the waste of electrical energy.