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1.2 Maximum Power
Products covered in this manual are limited to a maximum power of 360 MW. During set-up,
primary voltage and current setting are checked and the unit will not accept entries that breach
the 360 MW limit. This is covered in more detail in the sections that show primary voltage and
current set-up. The Maximum Power restriction of 360 MW refer to 120% of nominal current and
120% of nominal voltage, i.e. 250 MW nominal system power.
1.3 Secondary Voltage
0240 0340 0440 0640 1000 1540
Most of the products described in this manual allow the user to specify, within a range, the
secondary voltage of the potential transformer (PT) with which it is to be used. The exception is
the Integra 1000 and self contained Integra 1540, which has the PT secondary factory set. On the
Integra 1000/1540, the user cannot change this value.
1.4 Demand Calculation
0240 0340 0440 0640 1000 1540
The maximum power consumption of an installation is an important measurement, as most
power utilities base their charges on it. Many utilities use a thermal maximum demand indicator
(MDI) to measure this peak power consumption. An MDI averages the power consumed over a
number of minutes, reflecting the thermal load that the demand places on the supply system.
The Integra uses a sliding window algorithm to simulate the characteristics of a thermal MDI
instrument, with the demand being calculated once per minute.
The demand period can be reset, which allows synchronisation to other equipment. When it is
reset, the values in the Demand and Maximum Demand registers are set to zero.
Demand Integration Times can be set to 8, 15, 20 or 30 minutes.
The number of sub-intervals, i.e. the demand time in minutes, can be altered either by using the
Demand Integration Time set-up screen (see Section 3.8) or via the RS485 port, where available,
using the Modbus
TM
protocol.
During the initial period, when the elapsed time since the demands were last reset or since the
Integra was switched on is less than one minute, the maximum demands (current MaxAD and
power MaxkWD) will remain at zero and not follow the instantaneous demands.
Maximum Demand is the maximum power or current demand that has occurred since the unit
was last reset as detailed in Section 3.9 Resets.
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Integra 1540, 1000, 0640, 0440, 0340, 0240 Issue 1 04/03