Siemens MJ-5 Installation And Operation Manual page 27

4 Setting Up the MJ-5 Control Panel
Date
The Date data item allows you to set the real-time calendar.
Use the format selected in the Format item. If the format
defined below is MO/DA/YR, enter the date as 09/30/
07.
Format
The Format item allows you to set the format for the Date.
Daylight Sav (Daylight Savings Time)
The Daylight Sav data item automatically adjusts the clock
for the time changes on the second Sunday in March and
the first Sunday in November.
4.3.23 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).
The MJ-5 Control Panel accumulates demand values for
Load Voltage, Source Voltage, Compensated Voltage,
Load Current, kW, kVAR, and kVA. In addition, Power
Factor 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, and when power flow direction changes.
When a demand value is reset, dashes '-' appear on the
display screen until completion of the first demand period.
The MJ-5 Control Panel provides two methods of
computing demand: the Sliding Window method and the
Thermal 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 values for the oldest subperiod are discarded and new
demand values are calculated.
The DmdTime parameter specifies the number of minutes
in the period; the DmdSubperiods parameter specifies 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.
To use the Sliding Window method, view Dmd Type and
specify WINDOW. Then view DmdTime and specify the
length of the period in minutes (1 to 999); view DmdSub-
periods and specify the number of subperiods as a number
between 1 and 99.
Siemens Industry, Inc.
Thermal Method
The Thermal method is typical of the characteristic time lag
of mechanical or thermal devices as they absorb electrical
energy. It is based on the Code for Electricity Meters,
ANSI C12-1975, which defines the interval of a thermal
demand meter as the time required for the meter to indicate
90% of a change in the load. Demand values are updated
once each second.
For example, if you specify DmdTime = 15, the demand
meter indicates 90% of a steady load fifteen minutes after
the load is applied. In the next fifteen minutes, it responds
to 90% of the remainder of the total load. As a result, the
load is constantly averaged and transient variations are not
reflected.
Note: The Demand Subperiod data item is ignored by the
Thermal method.
4.3.24 Min/Max t.o. (Min/Max Time Out)
The Min/Max t.o. data item defines the length of time that
the Min/Max data items will be presented at the display
screen. At the end of this period, the display returns to the
present value.
To specify the Min/Max timeout period, view Min/Max
t.o.; use the Change/Save key and the Scroll keys to define
the number of seconds in the time-out period. Then press
the Change/Save key to complete the change process.
4.3.25 Screen t.o. (Screen Time Out)
The Screen t.o. data item defines the length of time that any
data item is displayed. At the end of the timeout period, the
display returns to the default display defined by the DspScr
data item.
4.3.26 Quick t.o. (Quick Time Out)
The Quick t.o. data item defines the length of time that the
Quick List data items will be presented at the display
screen. At the end of this period, the display returns to the
previous screen. See section 4.10.
4.3.27 QuickDispTim (Quick Display Time)
The QuickDispTim data item defines the length of time that
each data item in the Quick List will be displayed before
moving to the next item when the Quick List is in its slide
show mode. See section 4.10.
4.3.28 AutoVari-Amp
The AutoVari-Amp data item enables a capability that
automatically reduces the tap position based on the average
load current over the last 10 minutes compared to the I Full
Load. For example, if the regulator is at 105% of its rated
current on average for the last 10 minutes, the regulator will
not be permitted to move past 14 raise or lower and it will
move to 14 raise or lower if it is on a higher tap. If the
regulator is at 140% of its rated current on average for the
last 10 minutes, the regulator will not step past 8 to
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