Total Lifetime Hours; Alternation Of The Lead Pump; Staging / De-Staging In Mixed Pump Configurations - Danfoss MCO 101 Manual

Extended and Advanced Cascade Controller
Option

5.2.5 Total lifetime hours

For maintenance purposes, the extended cascade controller is designed to help you keep track of the total lifetime hours for each pump it controls.
The Pump Total Lifetime Hours parameter 27-04 displays a running total of the operating hours for each pump. This parameter is updated whenever a
pump is running, and it is saved to non-volatile memory once every hour.
This parameter can also be set to an initial value to reflect the hours of operation for a pump before it was added to the system.
Lifetime hours will only be accumulated by the cascade controller if it is enabled and controlling the pump.

5.2.6 Alternation of the Lead Pump

In a configuration with multiple drives, the lead pump is defined as the last variable speed pump running.
In a configuration with only a single drive, the lead pump is defined as the pump that is connected to the drive. More than one pump can be connected
to the drive through contactors that are controlled by the master drive's relays.
Through normal staging and de-staging, the cascade controller will alternate the lead pump to balancing running hours. It will also alternate the lead
pump when starting the system or when exiting sleep mode.
However, if the system demand remains below the maximum capacity of the lead pump for a long period of time without entering sleep mode, then it
will not alternate the pump. If this scenario is likely to occur, the lead pump can be forced to alternate through a Time Interval parameter 27-52 or
through a Time of Day parameter 27-54.

5.2.7 Staging / De-staging in Mixed Pump Configurations

Two methods are used to decide when pumps should be staged or de-staged. The first is the speed of the drives. The second is the feedback pressure
going outside of the normal operating range. In a Mixed Pump configuration with more than one drive, both methods are used.
In the following example, feedback is referred to as pressure.
Staging:
When the master drive receives a start command, a variable speed pump is selected and started using one of the available drives.
If the system pressure drops, the speed of the drive increases to meet the demand for more flow. While maintaining the pressure, if the drive exceeds
the Stage on Speed (27-31), and remains above that speed for the Staging Delay (27-23) time, the next variable speed pump is staged on. This repeats
for all of the variable speed pumps.
If the cascade controller is still unable to maintain the system pressure with all of the variable speed pumps on at maximum, it will begin to stage on
fixed speed pumps. A fixed speed pump will be staged on when the pressure goes below the setpoint by the Normal Operation Range (27-20) percentage
and stays there for the Staging Delay (27-23) time. This repeats for all of the fixed speed pumps.
De-staging:
If the system pressure increases, the speed of all of the drives decrease to match the system's reduced demand for flow. While maintaining pressure, if
the drive goes below the Stage off Speed (27-33) and stays there for the De-staging Delay (27-24) time, a variable speed pump will be staged off. This
repeats for all of the variable speed pumps except the last one.
If the system pressure is still too high with only one drive running at minimum speed, it will begin to de-stage fixed-speed pumps. A fixed-speed pump
will be de-staged when the pressure goes above the setpoint by the Normal Operating Range (27-20) percentage and stays there for the De-staging
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MI.38.C2.22 - VLT is a registered Danfoss trademark
5 Cascade Controller Features
5
5-3