American Dryer Corp MLS-460 manual Temperature Sensing Component Descriptions

1.TEMPERATURE SENSING COMPONENT DESCRIPTIONS

•Exhaust RTD (Resistive Temperature Device) - Sens1

The RTD (Resistive Temperature Device), used throughout the MLS-460 are identical. The main function is to measure temperatures and to transfer this information to a measuring device for further processing. The RTD used on the MLS-460 are rated for 1100° F (593.3° C).

•Sens2 = Exhaust Temperature Sensor

The exhaust RTD (Resistive Temperature Device) is located in the MLS-460 burner area exhaust duct and also has electrical disconnects in a junction box for ease of replacement.

•Exhaust 4 to 20 milliampere (4 to 20 mA) transmitter - Trans1

This transmitter is located on the upper right of the main electrical enclosure panel. The intake and exhaust RTD (Resistive Temperature Device) are respectively connected in series with a 24 volt DC power supply, and the current drawn from the power supply is 4 to 20 milliampere (4 to 20 mA) output signal which is proportional to the input signal. The proportional current information is the connected to the PLC (Programmable Logic Controller) for processing. Refer to the MLS-460 Ladder Diagram for circuit information.

•24 Volt DC Power Supply

The 24 volt power supply used in the MLS-460 is an individual grade switching power supply, rated for

120 volts AC input and 24 volts DC output. The features that this device incorporates are:

•Overload protection to protect the LOAD

•Internal failure protection to protect itself

•An output status indicator; this L.E.D. (light emitting diode) indicates the presence of DC output voltage.

•PLC (Programmable Logic Controller) Analog Input Module - Module #2

This device, attached to the PLC, receives the 4 to 20 milliampere (4 to 20 mA) temperature information and processes this information for the PLC

•Temperature Measurement and Sensing Problems

An “EXHAUST DSFL” MESSAGE is displayed on the operator terminal any time a respective temperature measurement has exceeded the programmed temperature in the PLC (Programmable Logic Controller). A “DSFL” message will stop the current drying cycle and prevent a drying cycle from starting.

2.EXHAUST “DSFL” MESSAGE a. PROBABLE CAUSES;

1)Defective RTD (Resistive Temperature Device) Probe

2)Defective 24 Volt DC Power Supply

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