TEMPERATURE CONTROL DEVICE FOR DIRECT ELECTRICAL HEATING TYPE SALT BATH FURNACE

摘要

PURPOSE:To provide a titled temp. control device which measures and controls furnace temp. by a method having reliability and durability by combining the output signal of a meter relay type ammeter, a repeated conduction signal for limiting time, a power source switch and the latching contacts of the power source switch. CONSTITUTION:A power source switch 4 operates to pass heating current to a salt furnace 1 when said furnace is set in the heating up state for ordinary use of the salt bath furnace and when the conducting contacts T.a for limiting time of a timer 9 are conducted by said timer. If the current is smaller then the set current value of a meter relay type ammeter 7, the control output contacts C, L are conducting and therefore the heating current continues to flow as it is to the furnace 1. The pointer of the ammeter 7 exceeds the set current value if the heating current increases upon increasing of the temp. in the furnace 1. The switch 4 is interrupted when the contacts C, L of the ammeter 7 open at the same instant as said increase, then no more heating current flows. The current of the furnace 1 is thereafter automatically maintained within a specified range (during operation of M.S) by the control to trigger the signal of the timer 9 in the above-mentioned way.