Siemens MJ-XL Installation And Operation Manual page 25

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The MJ-X Control Panel senses the reversal and modifies
its operation based on the Power Flow Mode selected.
This section provides an introduction to each of the
modes, and describes how to select the desired mode.
See Chapter 7 for a detailed discussion of the operational
differences between the modes.
Forward Locked Mode
This mode of operation (F LOCK) is intended for use in
systems where reverse power flow is not anticipated. Tap
changes are inhibited under reverse power flow condi-
tions.
Reverse Locked Mode
This mode of operation (R LOCK) is intended for use in
systems where forward power flow is not anticipated. Tap
changes are inhibited under forward power flow condi-
tions. For this mode a Source-side Potential Transformer is
no longer required. See Sections 5.1 and 5.2.
Bi-directional Mode
This mode of operation (BI-DIR) is intended for use in sys-
tems where reverse power flow is anticipated and voltage
regulation is desired under both forward and reverse
power flow conditions. For this mode a Source-side Poten-
tial Transformer is no longer required. See Sections 5.1
and 5.2.
Idle Reverse Mode
This mode of operation (IDLE R) is intended for use in sys-
tems where reverse power flow is to be treated as an
abnormal situation. When reverse power flow is recog-
nized, the regulator idles at the last tap position held
before the reversal.
Neutral Reverse Mode
This mode of operation (NEUT R) is intended for use in
systems where reverse power flow is to be treated as an
abnormal situation. When power flow reversal is recog-
nized, the regulator returns the tap changer to the neutral
tap position.
Co-Generation Mode
This mode of operation (CO-GEN) is for use in systems
where consumer-generated power may sometimes flow
from the consumer to the Utility. Under reverse current
flow conditions, forward regulation is allowed, using
reverse Line Drop Compensation settings.
4.3.16 PT Threshold (Potential Transformer
Threshold)
The PT Threshold data item defines a low-voltage thresh-
old. This parameter allows you to specify a voltage level
below which automatic mode tap changes will be inhib-
ited.
Siemens Power Transmission & Distribution, Inc.
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Setting Up the MJ-XL Control Panel
4.3.17 Time and Date Items
Time (Time of Day)
The Time data item allows you to set the real-time clock.
Specify the present time, TIME: HH:MM:SS A/P (e.g.,
04:34:54P).
Date
The Date data item allows you to set the real-time calen-
dar. Use the format selected in the Format item. If the for-
mat defined below is MO/DA/YR, enter the date as 09/30/
98.
Format
The Format item allows you to set the format for the Date.
4.3.18 Demand Methods
Demand values are system parameters that have been
averaged over a user-defined time period. Demand values
are accumulated separately for both forward and reverse
power flow conditions. Demand values can be viewed in
the Forward and Reverse <DEMAND> Menus. (See
Chapter 5.)
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The MJ-X Control Panel accumulates demand values for
Load Voltage, Source Voltage, Compensated Voltage,
Load Current, kW, kVAR, and kVA. In addition, Power Fac-
tor is stored whenever a new kVA maximum or minimum
is recognized.
Demand calculations are reset at the following times:
• system power up.
• when demand configuration items are changed.
• when power flow direction changes.
When a demand value is reset, dashes ' -' appear on the
display screen until completion of the first demand period.
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The MJ-X Control Panel provides two methods of com-
puting demand: the Sliding Window method and the Ther-
mal averaging method.
Sliding Window Method
The Sliding Window (or rolling interval) method divides the
time interval into subperiods. Meter values are individually
recorded once each second. At the end of each subperiod
an average value is derived for each Meter value; the val-
ues for the oldest subperiod are discarded and new
demand values are calculated.
The DmdTime parameter specifies the number of min-
utes in the period; the DmdSubperiods parameter speci-
fies the number of subperiods in the demand period. For
example, a DmdTime of 30 minutes and a DmdSubperiod
of 6 subperiods defines a thirty minute sliding window
that moves every five minutes.
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