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in Stand-By mode. To prevent excessive cycling, rate of pressure decrease is monitored;
if the pressure is decreasing at a rate that would cause the compressor to restart within
too short a time after entering Standby, the compressor will not enter Standby.
Once the compressor has entered Standby mode, pressure decrease is monitored; if
pressure is decreasing at a rate that will require the compressor to restart in a short time,
it will restart immediately, to enable the compressor to finish the startup sequence and
load immediately when air is required.
The compressor controls can also be shut down if the engine has been shut off for a
significant period of time, to conserve battery power.
WARNING: “STANDBY ACTIVE” indicates that the compressor may start
automatically at any time. THE COMPRESSOR IS NOT OFF. Do not
perform service if STANDBY is indicated.
The default delay time preset based on the KNW model. The set point is adjustable and
can be modified using the HMI (see Description of Operations).
If the system pressure drops below the Load setpoint, the compressor will automatically
restart.
5. Electrical Controls
NOTICE:
For a detailed description of HMI operation and navigation see the “Description
of Operation” Manual for the PLC program provided with the compressor. The
program number can be found on the KNW Title page accessible using the NAV
menu, and is shown on a label on the back of the HMI.
5.1. Compressor Control Panel
KNW Series air compressors come with a color HMI with touch screen. The HMI shows
current operating conditions, pressures, and temperatures. Messages to direct the
operator for service, pre-alarms, and shutdowns will be shown when necessary.
Required settings for pressure control, temperature alarms, and control time delays are
viewable and may be modified using the touchscreen. The HMI will automatically ‘dim’ to
a sleep condition if inactive and awakens on any touch contact.
The Beijer X2-Pro7 is the HMI used for standard KNW Series air compressors. The
Beijer X2-Extreme is fitted to the GPKD-1550-H Rental for increased durability. Consult
your local distributor for more information.
Pilot lights, viewable from a distance, are provided on the control panel for quick
indication of operating conditions, and an audible alarm is provided for annunciation.
Push buttons and a key-switch are provided for specific control functions, allowing
continued compressor operation in the event that the HMI is off-line.
The compressor control panel includes several additional monitoring devices which
operate independently of the PLC:
•
Voltmeter
: measures voltage to the compressor controls. This voltage should be
'24' during normal operation; a lower voltage may indicate failing batteries or charging
components.