TM 10--3510--221--24
0007 00--3
CONTROL SYSTEM THEORY
OF OPERATION -- Continued
0007 00
LEVEL, PRESSURE, AND TEMPERATURE SENSOR MONITORING
The analog card (PCB1) and analog--to--digital converter card (PCB11) provide the interface between the level,
pressure, and temperature sensors used to monitor key system parameters and PCB9. The level and pressure
sensors receive 12 VDC power from PCB1 and provide a 1--6 VDC signal back to the card. To monitor temperature,
resistance temperature devices (RTDs) are used. The resistance of these sensors change as the temperature
changes. These sensors provide an input to PCB1. PCB1 and PCB11 convert this resistance to a DC voltage and
provide an input signal to PCB9.
SWITCHING DEVICE MONITORING
Most switching devices used on LADs use 0 or +12 VDC signals to communicate with PCB9. These devices receive
+12 VDC through individual circuits on PCB2. If the switching device contacts are closed a +12 VDC input received
from the device will be provided as inputs to PCB8 through individual circuits on PCB2. PCB8 takes the 0 or +12 VDC
inputs received from PCB2 and provides a 0 or +5 VDC input to PCB9. The switching devices using 0 or +12 VDC
include:
Drum door and lock position switches (ZS100, ZS101, and ZS200)
Drum rotation proximity switch (ZS102)
Drum balancing limit switch (ZS103)
Emergency stop switch (PB6)
Anti--foam and detergent flow switches (FS200 and FS100)
Inverters (K100, K104, K200, and K500)
Motor protector overloads (OL101, OL104, OL105, OL200, OL201, OL300, and OL301)
Operator panel pushbutton switches (PBS1 through PBS5)
A few switching devices used are connected to 110 VAC circuits. These devices are connected to an interlock circuit
in the flame programmer. These devices also communicate through individual circuits with PCB9 through PCB3 and
PCB7. If the switching device contacts are closed the flame programmer interlock circuit will be continuous and a 110
VAC signal will be supplied to individual solid--state relays (SSR) located on PCB3. When energized the SSRs will
supply a +5 VDC signals to PCB7. PCB7 then provides +5 VDC inputs to PCB9. The switching devices using 0 or
110 VAC include:
Thermal fluid temperature limit switch (TS300)
Blower air inlet pressure switch (PS300)
Blower outlet pressure switch (PS301)
Flame programmer (FP300)
Fuel pressure switch (PS302)
MOTOR CONTROL
Operation of the motors used on the LADS is controlled using various methods. The small fractional HP,
single--phase motors are turned on and off using SSRs, When the SSR receives a 5 VDC input signal from PCB9,
through PCB7, the relay switches and applies 110 VAC power to the appropriate motor. When the 5 VDC signal is
removed the SSR switches and power is removed from the motor. The 3--phase motors that are not sensitive to
frequency changes in the input power are turned on and off in the same manner except that the SSR applies110 VAC
power to the coil of a contactor. When the coil is energized the contactor closes and 3--phase input power is supplied
to the motor. For those motors that will only operate at 60 HZ or operated at various speeds inverters are use. The
inverters compensate for frequency changes from the external power source to ensure that the motor speed remains
constant. The inverters connected to drive motors (M100) also communicate with the processor to control the speed
of the motors during tumble and extract.
