Cool air blower for oven switchgear compartment - has two temp. sensitive switches controlling speed during heating and cooling phases of oven

摘要

The main oven switch (8) closes the power supply circuit to a series resistor (14) and the blower drive motor (M). A first temperature sensitive switch (16) shunts the switch (8) and cuts in at 50 deg.C. The motor runs then at a speed of 1500 rev/min. At a temperature of 55-60 deg.C, a second similar switch (17) shunts the resistor and the motor runs at its full speed of 2300 rev/min. The circuitry for the drive of the blower is based on running the motor at different speeds by one or two temperature sensitive switches, depending on whether the oven is used for normal baking duties or for a pyrolytic self-cleaning cycle. This effectively reduces the noise emitted by the blower to a minimum and saves energy by a step-by-step speed control during both the heating and the cooling cycle.