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6
MJ-4A & MJ-4B Control Panel Automatic Mode
6 MJ-4A & MJ-4B Control Panel Automatic Mode
This Chapter covers operating principles of the MJ-4 con-
trol program and describes the various functions per-
formed by the microprocessor. It contains the information
you may need when deciding between the various options
described in Chapter 4 (Setting Up the MJ-4 Control Panel)
and Chapter 5 (Reading and Interpreting MJ-4 Control
Panel Data).
6.1
MJ-4A & MJ-4B Control Modes
6.1.1 Summary of the MJ-4A Control Modes
The regulator control function has four operating modes:
local manual control, local automatic control, remote con-
trol, and Off. Manual control can only be performed locally.
Select the operating mode with the Remote-Auto/Off/
Manual switch as shown in Figure 6.1.
A u to
O ff
(B y-P ass
P o sitio n)
M a nu a l
Figure 6.1
Auto/Manual Switch (Shown in Off position)
Manual mode
Place the Auto/Off/Manual Switch in the down position to
activate the Manual mode. In Manual mode, you can use
the Tap Raise/Lower switch (on the MJ-4A front panel) to
control the tap position directly. Status information is avail-
able via the remote communications link, but the remote
operator cannot change settings or otherwise operate the
MJ-4A Control Panel.
Off (By-Pass Position)
No operation of the tap changer can occur: remotely,
locally, or automatically.
Auto-Remote mode
With the Auto/Manual switch in the up position, the
Remote/Local key may be pressed so that the Remote
Disabled LED is off, putting the control Panel into the
Auto-Remote mode.
In this mode, the MJ-4A executes its automatic tap con-
trol algorithms, unless overridden remotely. Status infor-
mation is available via the remote communications link. A
remote operator can request a tap raise or lower via the
communications link, change settings and remotely oper-
ate the control program. For direct control via terminal
strip connections see Figure 2.4.
When the remote operator initiates the tap raise/lower,
the MJ-4A enables its "Pseudo-Manual" operating mode.
The Pseudo-Manual alert condition is activated, and local
automatic operations are disabled until the remote-com-
manded tap raise/lower is completed.
46
R em o te
/
L o ca l
The MJ-4A Control Panel remains in the Pseudo-Manual
mode for a predefined time period after receipt of the last
remote tap raise/lower command. When the time period
has elapsed, if the MJ-4A Control Panel has Remote Auto
Inhibit disabled, it resumes its normal automatic control
operations. If Remote Auto Inhibit is enabled, it maintains
its tap position until it recieves another raise/lower com-
mand or until Remote Auto Inhibit is disabled.
Auto-Local mode
With the Auto/Manual switch in the up position, if the
Remote/Local key is pressed so that the Remote Disabled
LED is on, the control Panel will be in the Auto-Local
mode. In this mode, the MJ-4A executes its normal tap
control algorithm. Status information is available via the
remote communications link, but the remote operator can-
not change settings or otherwise operate the MJ-4A Con-
trol Panel
6.1.2
Summary of the MJ-4B Control Modes
The regulator control function has four operating modes:
manual and automatic control, each with remote control
enabled or disabled. Select the operating mode with the
Remote and Auto/Manual switches as shown in the figure
below.
R e m o te
/
L o c a l
Figure 6.1b Remote/Local and Auto/Manual Switches
Manual mode (By-Pass Position)
Push the Auto/Manual Switch so that the Auto Disabled
LED is illuminated to activate the Manual mode. In Manual
mode, you can use the Tap Raise and Lower keys (on the
MJ-4B front panel) to control the tap position directly.
Automatic mode
Push the Auto/Manual Switch so that the Auto Disabled
LED is not illuminated to activate the Automatic mode. In
Automatic mode, the MJ-4B executes its normal tap con-
trol algorithm.
Remote Control Enabled
Push the Remote / Local push button so that the Remote
Disabled LED is not illuminated to enable remote control
(Auto-Remote mode). In this mode, the MJ-4B executes
its automatic tap control algorithms, unless overridden
remotely. A remote operator can request a tap raise or
lower via the communications link. When the remote
operator initiates the tap raise/lower, the MJ-4B enables
its "Pseudo-Manual" operating mode. The Pseudo-Man-
ual alert condition is activated, and local automatic opera-
tions are disabled until the remote-commanded tap raise/
lower is completed.
A u to /
M a n u a l
Siemens Energy, Inc.
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