Allen-Bradley Powermonitor 3000 User Manual page 347

Glossary 23
slave address
This is the numerical label for slave devices. Valid slave device
addresses are in the range of 0 to 247 decimal. The individual slave
devices are assigned addresses in the range of 1 to 247. The value of 0
is reserved for broadcast.
sliding demand interval
A method of calculating average demand by averaging the average
demand over several successive short time intervals, advancing one
short time interval each time. Updating average demand at short time
intervals gives the utility a much better measure of true demand and
makes it difficult for the customer to obscure high short-term loads.
sub function code
Sub function word: third and forth bytes of any Modbus Command
packet.
unbalanced load
A situation existing in a three-phase alternating current system using
more than two current carrying conductors where the current is not
due to uneven loading of the phases.
volt-ampere (VA)
The unit of apparent power. It equals volts times amperes regardless
of power factor.
volt-ampere demand
Where peak average demand is measured in volt-amperes rather than
watts. The average VA during a predefined interval. The highest
average, i.e. Peak VA demand, is sometimes used for billing.
voltage (V)
The force which causes current to flow through a conductor. One volt
equals the force required to produce a current flow of one ampere
through a resistance of one ohm.
watt (W)
A measure of real power. The unit of electrical power required to do
work at the rate of one joule per second. It is the power expended
when one ampere of direct current flows through a resistance of one
Allen-Bradley HMIs ohm. Equal to apparent power VA times the power factor.
Publication 1404-UM001D-EN-E - October 2004