User Manual EML1101
Annex
20 Appendix
20.1 Glossary of Terms
Maximum demand
– The maximum amount of power drawn, measured in kW, during a measuring
period.
Measuring period
– The time period which
EML 1101
limits
maximum demand
to
target maximum
demand
for different profiles. Normally electricity companies provide time pulses that indicate the
start and end of a
measuring period
. An internal reset for measuring period will occur if the
EML
1101
does not receive a time pulse that indicates the end of a measuring period. Also, time pulse
edge determines which edge of the time pulse is used to indicate the start of a new
measuring
period
.
Remaining time
– Time required to reach the end of current
measuring period
.
Target maximum demand
– an arbitrary limit used by
EML 1101
control system so that average
powers do not exceed this limit.
Accumulated power
– Amount of energy measured since the beginning of current measuring period
divided by the duration of measuring period. It is abbreviated by
P_acc
.
Trend power
– The extrapolated accumulated power based on energy consumption trends when end
of current measuring period is reached. It is abbreviated by
P_trend
.
Profiles
– This feature enables different settings to be used by
EML 1101
to cater for the following
conditions:
•
Tariff switching triggered by electricity companies.
•
Different production requirements.
•
Time dependent loads.
Control application point
– Sets
P_acc
level for
EML 1101
to start limiting
P_trend
to
target
maximum demand
. Monitoring and control is immediately active at the start of a measuring period
(see figure below).
P_trend
is allowed up to twice the
target maximum demand
value initially.
Then, it is reduced linearly with
P_acc
until
control application point
.
P_trend
is limited to
target
maximum demand
after
control application point
.
Emergency mode
– A condition activated when the control characteristics can no longer be
maintained under pre-set conditions. The following characteristics are valid during emergency mode:
•
Minimum ON time and maximum OFF time are ignored. Minimum OFF time, however, is
still taken into account.
•
Loads with priorities 1 to 3 are included in the control system.
•
The emergency load shedder channel is activated if
EML 1101
cannot reduce
P_trend
within limits during this mode.
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