49
Key:
BLUE Solid
Steady Blue
RED Solid
Steady Red
Blue w/ Red Slow Flash
(300ms every 3 sec)
Blue w/ Red Med Flash
(300ms every 2 sec)
Blue w/ Red Fast Flash
(300ms every 1 sec)
Blue
Fast
Flash
(400ms
every
0.8
sec)
Blue/Red Flash
(400ms/400ms)
Disabled-AR
Disabled state from Auto Reset sequence
Disabled-PB
Disabled state from manual (Push Button) RESET
6.3.1 Acquire
In the
ACQUIRE
state, the MACS/D system establishes a baseline value corresponding to the average ambient
magnetic field at the triaxial probe and stores this value in the form of axial constants. During subsequent
system operation, the axial constants are subtracted from the probe input axial values so that only error terms
corresponding to the interference signals remain. An
ACQUIRE
operation occurs when power is initially applied
to the MACS/D system, when the system has recovered from a Power Trip, when it has automatically recovered
from a LEVEL Trip, or anytime the front panel RESET pushbutton is pressed and released.
During normal baseline acquisition sequencing, the probe baseline signal is averaged for approximately 6
seconds after which the MXA controller advances to a
RAMP UP
state for about 11 seconds to bring the Coil
Driver Amplifier (CDA) on line. If the system is in an operational configuration, the controller passes through
a
SETUP
state to the normal
OPERATE
state of full magnetic field compensation in a total elapsed time of
approximately 16 seconds.
In the case of a newly installed system where the axial Output Gains have not yet been adjusted and interfering
fields exist at the fluxgate probe location in excess of one or more axial Trip threshold levels (see
Figure 14, (49)
for adjustment screen), the system will enter its
SETUP
state instead of the normal
OPERATE
state.
6.3.2 Setup
A
SETUP
state has been incorporated in the system to prevent nuisance
OVERLEVEL
Trips during the initial
setup procedure. When the system is first turned on, with the Output Gain sliders preset to low levels, interfering
signal levels can exist in the PV that may exceed one or more of the preset Trip levels, a condition that would
normally cause the system to initiate an automatic reset sequence after only a few seconds, before the Output
Gain adjustments could be made. The
SETUP
state avoids this problem by ignoring a Trip
OVERLEVEL
condition
if it is detected the first time the system comes on line from a
manual
RESET
pushbutton (
RESET-PB
) action.
SETUP state is entered when the system leaves the
RAMP-UP
state that follows the
ACQUIRE
state. If there are
no faults but the X, Y or Z levels are above the trip setting, the unit will stay in the
SETUP
state for the purpose of
setting the Output Gain sliders.
If there are no faults and the X, Y and Z levels are below the Trip settings, the unit will proceed to its normal
OPERATE
state. To correctly set the Output Gain levels in the
OPERATE
state when the uncompensated
interfering signals are exceptionally low, see
Section 5.3
.
