Alemite Carbon Shield, Installation, Operation And Maintenance Manual

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10 | alemite Carbon Shield Service Sheet
Human Machine Interface (HMI)
The touch screen on the front of the Carbon
Shield
™
cabinet is an HMI (Fig.04) which provides
a color visual display of system status, parameter
values and alarm conditions. The HMI is also the
access port for set up and programming of the
system parameters at start up. The HMI is
connected to the PLC by a communication cable.
PLC Password Information
User names and passwords are factory set and
provided at the time of delivery. They allow the
appropriate access to the two password protected
screens in the HMI. The administrator user name
and password grants access to Set Up and Change
Parameters screens. The supervisor password
access is limited to the Change Parameters screen
only. All other screens in the HMI are for viewing/
information and do not require password.
the PLc receives:
• 4-20 mA signals from the pressure/vacuum
sensors that indicate mist head and mist
outlet pressure
• Air and oil temperature signals from
thermocouples installed in the air and
oil streams
• 4-20 mA signals from the oil level sensor
the PLc sends:
• 4-20 mA control signals to the transducer/
regulator for air pressure/mist pressure control
• Digital outputs to DC interposing relays
to control:
– air heater
– Oil heater
– Local status red light on top of cabinet
– Local status green light on top of cabinet
– Remote status light or buzzer
in control room
– Oil input refill solenoid
should the level sensor or any transducer/
transmitter indicate an abnormality, the PLc:
• Illuminates the red light on top of the cabinet
• Displays an alarm message on the HMI
Fig. 04