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8.7.20 Pump start and stop speed (4.2.8)
Description
The function controls the starting and stopping of pumps. There
are two options:
1. Use calculated speed: This function ensures that the optimum
number of pumps always run at a desired duty point, in terms
of energy consumption. CU 352 estimates the pump data,
which is required to calculate the optimal number of pumps
and their speed. This requires that the differential pressure of
the pump and the power of each pump are measured. The
differential pressure can be measured either by a sensor or
separate pressure sensors on the inlet and outlet side. If
calculated speed has been selected, CU 352 ignores the
percentages set.
2. Use fixed speed: The pumps are started and stopped at
speeds set by the user.
1. Use calculated speed
Fig. 59 Use calculated speed
Setting via the operating panel
• Settings > Pump cascade control > Pump start and stop speed
> Use calculated speed > Start pump data estimation.
2. Use fixed speed
Fig. 60 Use fixed speed
Setting via the operating panel
• Settings > Pump cascade control > Pump start and stop
speed.
• Select: Use fixed speed.
• Set: Start next pump at this speed > 1 -> 2.
1. Set the speed as percentage.
2. Set the other pumps in the same way.
3. Select: Instant pump stop at > 1 -> 0.
4. Set the speed as percentage.
5. Set the other pumps in the same way.
Factory setting
The function is set to calculated speed.
8.7.21 Min. performance (4.2.9)
Fig. 61 Min. performance
Description
The function ensures circulation in a system. Note that the stop
function, if enabled, can influence this function. See section
8.7.24 Stop function (4.3.1). Examples:
• If zero pumps have been selected, the stop function can stop
the pump if there is no or a very small consumption.
• If pumps have been selected, the stop function will not be
active.
Setting via the operating panel
• Settings > Pump cascade control > Min. performance.
1. Set:
• Number of pumps
• Speed.
Factory setting
The number of pumps is set to zero. The speed in closed loop is
set to 25 %.
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