Sterlco GH-M Series Extrusion Control Weigh Hoppers - Manual (Page 16)

Chapter 2: Functional Description 16 of 60
• Optional Ethernet communications
System Component Description
This section describes the various components of the rate monitor system.
Extruder Inductive Proximity Switch
The extruders RPM must be reported to all GH, GH-M, and GH-F Systems for them to
function. To accomplish this, an inductive proximity switch is provided to let the controller
know the RPM of the extruder. This switch should be field mounted in an appropriate way to
read the extruder’s true RPM. It is important this switch is reading the actual RPM of the
Extruder, and not an RPM before a gearbox, for example. Chapter 3 will detail the
installation and wiring of this component. Because it is field mounted, wiring of the
proximity switch will NOT be done at the factory and we do not provide any custom
mounting brackets for your application as these vary depending on the equipment.
This measurement can also be achieved by writing the extruder’s rpm through
communications (see document at the end of this manual for details, NOT AVAILABLE
FOR GH-F FEEER UNITS). If this is done through communications then it eliminates the
need to install the extruder proximity switch.
Surge Hopper
The surge hopper is located on top of the GH frame. These hoppers store a supply of material
to fill the weigh hopper. The surge hopper is sized based on the total throughput of the
extrusion rate monitoring system. Each surge hopper contains a 24V DC solenoid that is
used to open and close the internal dump cone. The internal urethane dump cone is
mechanically opened and closed with a compressed air cylinder.
The GH’s surge hopper does not include any level indication devices as standard equipment.
Optional surge hopper low-level sensors are available. The GH controller will alarm if it runs
out of material while trying to fill the weigh hopper, but low-level sensors will alert floor
personnel to the problem sooner. If an optional low-level sensor is purchased, it will activate
a visual alarm. This optional proximity switch can be mounted anywhere the customer
desires and is not mounted unless specifically requested.
The refill system is equipped with a manual key switch to open and close the surge hopper.
This three position key switch is located on the front of the PLC enclosure.
Figure 5: Typical Surge Hopper
Figure 6 Refill Switch Positions
Position Description
AUTO
The rate monitor controller automatically controls surge hopper
functions.