Siemens MJ-XL Installation And Operation Manual page 51

NEUT R (Neutral Reverse)
This mode of operation is intended for use on systems
where reverse power flow is an abnormal situation.
In this mode, the controller always operates in the for-
ward mode. When current magnitude drops below the
forward I Threshold % setpoint, tap changes are inhibited.
When the reverse current magnitude exceeds I Threshold
% setpoint for ten seconds, the tap changer resumes
operation and returns the tap changer to the neutral posi-
tion without stopping. The tap changer then remains at
the neutral position until forward current magnitude once
again exceeds the I Threshold % setpoint.
If, while the tap changer is returning to neutral, the for-
ward current magnitude increases above the I Threshold
% setpoint, normal forward tap changer operation
resumes.
If the I Threshold % setpoint is set to zero, the regulator
operates as above, using the 1% operational limits in
place of the I Threshold % setpoints.
Neutral Reverse mode is dependent upon the MJ-X
tracking algorithm. If the tap position is unknown to the
microprocessor, the tap changer idles at the last held posi-
tion.
View Pwr Flow: NEUT R on the <CONFIGURE> Menu.
Reverse Current
Return to
Tap Changes Inhibited
neutral
after ten
seconds
Continue return
to neutral
RPF indicator on
Band indicators flashing
I Threshold % 1%
Current
Neutral Reverse Mode
Figure 6.6
Siemens Power Transmission & Distribution, Inc.
6
L
tap
Forward Current
Forward
Operation
RPF indicator off
Band indicator
LEDs on
0 1% I Threshold %
MJ-XL Control Panel Automatic Mode
CO-GEN (Co-generation)
This mode of operation is for use on systems where
power flows from Utility to consumer at certain times and
from consumer to Utility at other times. In this mode, the
tap changer operates whenever current magnitude (either
forward or reverse) exceeds the I Threshold % setpoint.
In this mode, the controller always operates in Forward
mode. Forward Line Drop Compensation values are used
when forward current magnitude exceeds the I Threshold
% setpoint. Reverse Line Drop Compensation values are
used when reverse current magnitude exceeds the I
Threshold % setpoint. Tap changes are inhibited when
current magnitude is between the I Threshold % set-
points.
If the I Threshold % setpoint is zero, the regulator oper-
ates in the same manner as above using the 1% opera-
tional limits as the I Threshold % setpoints.
View Pwr Flow: CO-GEN on the <CONFIGURE> Menu.
Reverse Current
Reverse
Tap Changes Inhibited
Operation
with
Reverse
LDC
RPF indicator on
I Threshold %
Co-generation Mode
Figure 6.7
Forward Current
Forward
Operation
with
Forward
LDC
RPF indicator off
Band indicators flashing
1% 0 1% I Threshold %
Current
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