User Manual

45
AUTOMATIC CONTROL
3 COOLING CONTROL BT Grund der Energieeinsparung
3.3 Control of distribution network cold water
temperature (supply or return)
Similar function can be applied to the control of
direct electric cooling (e.g. compact cooling units,
split units) for individual rooms
0
Constant temperature control A constant, low design temperature of all
consumers is continuously provided in
distribution, resulting in significant energy losses
under part load conditions.
1
Outside temperature compensated control
Action generally raise the mean flow temperature
Distribution temperature is controlled depending
on the outside temperature (corresponding to
the probable temperature demand of the
consumers), considerably reducing energy
losses.
2
Demand based control
E.g. Indoor temperature control variable; Actions
generally raise the mean flow temperature.
Distribution temperature depends on the room
temperature (controlled variable). It considers
heat gains in the room as well (solar irradiance,
people, animals, technical equipment). Keeps
energy losses under part load conditions to an
optimum (low)
3
3.4 Control of distribution pumps in hydraulic networks
The controlled pumps can be installed at different
levels in the network
0
No automatic control
No savings, since electrical power for the pump
is drawn continuously.
1
On off control
To reduce the auxiliary energy demand of the
pumps
Electrical power for the pump is drawn only as
required – e.g. during occupancy or in protection
mode (overheating hazard).
2
Multi-stage control
To reduce the auxiliary energy demand of the
pumps
Operation at a lower speed reduces the power
consumption of multi-speed pumps.
3
Variable speed pump control
constant or variable Δp based on pump unit
(internal) estimations to reduce the auxiliary
energy demand of the pumps
8
a) With constant Dp: Pressure differential does
not increase at decreasing load when
maintaining a constant pressure differential
across the pump. The pump speed is
reduced under part load conditions, which
lowers the electrical power.
b) With variable Dp: Pressure differential
across the pump drops as the load
decreases. This provides additional
reductions in speed and electrical power
under part load conditions.
4
Variable speed pump control
variable Δp following an external demand signal,
e.g. hydraulic requirements, ΔT, energy
optimization to reduce the auxiliary energy
demand of the pumps
With variable Dp following an external demand
signal, the pump speed is reduced under part
load conditions as much as possible whilst
ensuring, that the consumer with the largest
demand is still satisfied at any given operational
situation, i.e. no underprovisioning of certain
consumers. This lowers power consumption
maximally.