Product User Manual
Page 18
EPRI Commercial Microwave Fabric Dryer
Gerling Applied Engineering, Inc.
Modesto, CA
screen then it will gradually reduce the flow of exhaust air to the
sensors, thus reducing their sensitivity.
To prevent continual accumulation of lint on the sensor screen the
lint is burned off at the end of every drying cycle by applying an
electrical current through the screen. This current is high enough to
cause the lint to smolder but not ignite into an open flame. The
burn-off period occurs after the blower stops so that the flow of air
does not prevent the burn-off temperature from being reached. The
lint ash is then carried away by the exhaust air at the start of the
next drying cycle.
Low Voltage Power Supplies
Several low voltage power supplies provide power to various
control circuits. These power supplies are on whenever line power
is connected to the CMFD and the main circuit breaker is turned on.
Their functions are described as follows:
•
24 VDC Power Supply – This power supply is the primary
source of control power to the CMFD. Several devices are
powered by this supply directly while others are powered
through additional circuitry. Devices connected to the output of
this power supply are protected by a 5 Amp fuse.
•
Gas Sensor Power Supply – This power supply is dedicated to
only the gas sensors to p5 VDC for heater power and
+10 VDC for signal power. This dedication is necessary to
maintain stability of the supply voltages to help prevent erratic
performance of the sensors.
•
Voltage Regulators – Two voltage regulators p15 VDC
to the humidity sensor and +5 VDC to the microprocessor and
various other devices and circuitry.
Drive Motors
Two different electric motors are used to drive the blower and dryer
basket. Both motors operate simultaneously during all periods of
dryer operation except when the buzzer is on (fault or end-of-cycle)
and during the sensor lint screen burn-off.
The blower is driven by a fixed speed AC motor while the basket is
driven by a variable speed DC motor. The speed of the basket
motor, and thus the basket rotation speed, can be varied by
adjusting a trimming potentiometer (R10) located near the bottom
edge of the microprocessor interface PC board.
CAUTION:
Excessive basket rotation speed can cause damage
to the internal basket support rollers and drive mechanism. The
basket speed should be such that the fabrics are allowed to fall
