Troubleshooting Based On Alert; Messages; Voltage And Current Calibration - Siemens MJ-4A Installation And Operation Manual

8
MJ-4A & MJ-4B Control Panel Basic Troubleshooting
8.3

Troubleshooting Based on Alert

Messages

Alert messages can be used to help diagnose both sys-
tem problems (ones which include both regulator and con-
troller), and internal MJ-4 problems. Table 8.1 provides
suggestions for troubleshooting an MJ-4 Control Panel
using information from the <ALERTS> menu.
Note that faults identified as "temporary" may be due to
transient conditions within the system and may not be
internal MJ-4 faults.
Note that faults identified as "temporary" may be due to
transient conditions within the system and may not be
internal MJ-4 faults.
8.4

Voltage and Current Calibration

The MJ-4 Metering functions are calibrated at the factory.
Periodically check calibration, and, if needed, recalibrate
the MJ-4:
8.4.1 Checking the U2 Voltage Calibration
Note: You can check the U2 voltage calibration while
the panel is installed on a regulator.
To check U2 calibration, apply an AC voltage (in the range
of 115 to 135 VAC) from U2 to E. Monitor the Voltage Cali-
bration/Test Terminals with a true RMS voltmeter. View
the "U2 Cal" screen on the MJ-4 (i.e., goto <DIAGNOS-
TICS> menu and press down arrow once to show "U2
Cal" . ) Verify that the "U2 Cal" reading matches the applied
voltage (within ± 0.5 VAC) If calibration is off, recalibrate
(see below.)
8.4.2 Checking the P2 Voltage Calibration
Note: If the regulator provides the "source" voltage
signal, you can check the P2 voltage calibration
while the panel is installed on the regulator. (If
the regulator lacks a "source" voltage signal,
then there is no need to calibrate the P2 input.)
To check P2 calibration, apply an AC voltage (in the range
of 115 to 135 VAC) from P2 to E. Monitor the Voltage Cali-
bration/Test Terminals with a true RMS voltmeter. View
the "P2 Cal" screen on the MJ-4 (i.e., goto <DIAGNOS-
TICS> menu and press down arrow twice to show "P2
Cal") Verify that the "P2 Cal" reading matches the applied
voltage (within ± 0.5 VAC) If calibration is off, recalibrate
(see below.)
8.4.3 Checking the Load Current Calibration
Note: To check the current calibration, remove the
panel from the tap changer apparatus, connect
an external ammeter, and apply an external AC
current source.
To check C/C2 Low calibration, apply a nominal 5 mA AC
current at C2/E1 and verify that "C/C2low" reads within
±0.2 mA of the applied value (as displayed on external
Ammeter connected at C/C2.)
56
To check C/C2 Medium calibration, apply a nominal 80 mA
AC current at C2/E1 and verify that "C/C2med" reads
within ± 0.5 mA of the applied value (as displayed on
external Ammeter connected at C/C2.)
To check C/C2 High calibration, apply a nominal 140 mA
AC current at C2/E1 and verify that "C/C2high" reads
within ± 0.7 mA of the applied value (as displayed on
external Ammeter connected at C/C2.)
8.4.4 Calibrating the U2 Voltage
Connect an external true rms voltmeter at the front panel
"Voltage Calibration/Test Terminal. " Apply the nominal cali-
bration voltage (per Table 8.2.) Display the "U2 Cal"
screen. To calibrate, press the Change key, then the
key to make the value shown on the MJ-4 display agree
with the external voltmeter value. When the change is
complete, press the Save key.
Note: If password protection is in effect, you must
enter the password to enable calibration. The
default password for the <DIAGNOSTICS>
Menu is "3333" .
8.4.5 Calibrating the P2 Voltage
Connect an external true rms voltmeter at the front panel
"Voltage Calibration/Test Terminal. " Apply the nominal cali-
bration voltage (per Table 8.2.) Display the "P2 Cal"
screen. To calibrate, press the Change key, then the
key to make the value shown on the MJ-4 display agree
with the external voltmeter value. When the change is
complete, press the Save key.
Note: If password protection is in effect, you must
enter the password to enable calibration. The
default password for the <DIAGNOSTICS>
Menu is "3333" .
8.4.6 Calibrating the Load Current
Note: To calibrate the current, disconnect the panel
from the tap changer apparatus. Remove on-
board jumper J1 (see Figure J.1) and Terminal
Strip jumper at P3B-11 & 12. Connect an exter-
nal ammeter, and apply an external AC current
source, per Table 8.2. After calibration, replace
J1 and Terminal Strip jumper at P3B-11 & 12.
The Load Current (Ild) has three calibration set-points:
C/C2 Low, C/C2 Medium, and C/C2 High. Calibrate all
three setpoints with an external true rms ammeter con-
nected at the rear panel (terminal strip contacts P3B-11 &
12.) Connect a (nominal) 0-200 mA AC current source at C/
C2 (terminal strip contacts P2A-5 & 7 .)
Apply the C/C2 Low calibration current (per Table 8.2). Use
the Menu and Scroll keys to view the "C/C2low" screen.
To calibrate, press the Change key, then the
make the value shown at the MJ-4 display agree with the
external ammeter value. When the change is complete,
press the Save key.
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