The Danfoss VLT® FC202 series drive comes with a built in basic Cascade Controller to allow control of up to 2 additional fixed speed pumps to maintain a system set point.
The Danfoss VLT® Extended Cascade Controller MCO 101 and VLT® Advanced Cascade Controller MCO 102 are option modules which can be fitted into a Danfoss VLT® FC202 series drive to allow control of up to 8 pumps in Cascade or Master / Follower setup to maintain a system set point.
Danfoss VLT® Built in Basic Cascade Controller
The BASIC Cascade Controller is used for pump applications where a certain pressure (“head”) or level needs to be maintained over a wide dynamic range. Running a large pump at variable speed over a wide range is not an ideal solution because of low pump efficiency at lower speed. In a practical way, the limit is 25% of the rated full load speed for the pump.
In the BASIC Cascade Controller the frequency converter controls a variable speed (lead) motor as the variable speed pump and can stage up to two additional constant speed pumps on and off. By varying the speed of the initial pump, variable speed control of the entire system is provided. This maintains constant pressure while eliminating pressure surges, resulting in reduced system stress and quieter operation in pumping systems.
Danfoss VLT® MCO101 Extended and MCO102 Advanced Cascade Controller
The MCO101 option card can be used to extend the built in functionality of the VLT® FC202 Cascade Controller by allowing up to 6 pumps in standard cascade or giving access to Master / Follower mode with a up to 5 pumps.
The MCO102 option card is an upgraded version of the MCO101 where it has additional functionality for Master / Follower mode and allowing up to 8 pumps to be controlled in both Standard Cascade Setup or Master / Follower Setup.
Use of MCO101 or MCO102 to extend a Danfoss FC202 built in basic cascade
In applications already controlled by the built-in cascade controller in group 25**, the option card can be used to extend the numbers of relays for cascade control. For instance if a new pump is added to the system. It can also be used in case it is wanted to alternate the lead pump in systems with more than 2 drives, which is the limit for the basic cascade without MCO 101 or MCO102 option installed.
Use of MCO101 or MCO102 Master / Follower Functionality
In this configuration each pump is controlled by a frequency converter. All of the pumps and frequency converters must be of the same size for the standard setup however a limited mix of Unequal size pumps and DOL pump can be configured. Staging and de-staging decisions are made based on the speed of the frequency converters. The constant pressure is controlled by the master drive operating in closed loop. The speed will be the same in all running pumps with extended control. Up to 6 pumps can be controlled via the MCO101 Option and 8 via the MCO102 Option.
All manuals and technical information for the Danfoss VLT® Basic Cascade Controller can be found in the FC202 AQUA Drive Design and Programming Guide which can be found here.
All manuals and technical information for the Danfoss VLT® MCO101 Extended and MCO102 Advanced Cascade Controller can be found here.