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Glossary-5
Quadrant: Watt and VAR flow is typically represented usng an X-Y coordinate system.
(Programmable The four corners of the X-Y plane are referred to as quadrants. Most power
Values and Factors applications label the right hand corner as the first quadrant and number the
on the EPM9450, remaining quadrants in a counter-clockwise rotation. Following are the
9650 & 9800) positions of the quadrants: 1st - upper right, 2nd - upper left, 3rd - lower left
and 4th - lower right. Power flow is generally positive in quadrants 1 and 4.
VAR flow is positive in quadrants 1 and 2. The most common load conditions
are: Quadrant 1 - power flow positive, VAR flow positive, inductive load,
lagging or positive power factor; Quadrant 2 - power flow negative, VAR flow
positive, capacitive load, leading or negative power factor.
Register: An entry or record that stores a small amount of data.
Register Rollover: A point at which a Register reaches its maximum value and rolls over to zero.
Reset: Logs are cleared or new (or default) values are sent to counters or timers.
Rolling Window The Rolling (Sliding) Window Average is the average power calculated over a
Average (Power): user-set time interval that is derived from a specified number of sub-intervals,
each of a specified time. For example, the average is calculated over a
15-minute interval by calculating the sum of the average of three consecutive
5-minute intervals. This demand calculation methodology has been adopted by
several utilities to prevent customer manipulation of kW demand by simply
spreading peak demand across two intervals.
RS232: A type of serial network connection that connects two devices to enable
communication between devices. An RS-232 connection connects only two
points. Distance between devices is typically limited to fairly short runs.
Current standards recommend a maximum of 50 feet but some users have had
success with runs up to 100 feet. Communications speed is typically in the
range of 1200 bits per second to 57,600 bits per second. RS-232 connection
can be accomplished using Port 1 of the EPM 9450/9650 or the Optical Port
on the face of the EPM 9800.
RS485: A type of serial network connection that connects two or more devices to enable
communication between the devices. An RS-485 connection will allow
multi-drop communication from one to many points. Distance between devices
is typically limited to around 2,000 to 3,000 wire feet. Communications speed
is typically in the range of 120 bits per second to 115,000 bits per second.
Sag: A voltage quality event during which the RMS voltage is lower than normal for
a period of time, typically from 1/2 cycle to 1 minute.
Secondary Rated: Any Register or pulse output that does not use any CT or VT Ratio.
Serial Port: The type of port used to directly interface with a PC.
Slave Device: In Modbus communication, a Slave Device only receives a Request Packet from
a Master Device and responds to the request. A Slave Device cannot initiate