Overview Of Control Variants - Grundfos Control MPC Installation And Operating Instructions Manual

5. Overview of control variants

The examples below are based on booster systems.
Systems with speed-controlled
pumps
Control MPC-E/-EC
E: Control MPC with three E-pumps.
EC: Control MPC with three pumps,
each connected to a Grundfos CUE
frequency converter.
PT
One E-pump in operation.
H
H
set
Three E-pumps in operation.
H
H
set
• Control MPC-E/EC maintains a constant
pressure through continuous adjustment
of the speed of the pumps.
• The system performance is adjusted to
the demand through cutting in/out the
required number of pumps and through
parallel control of the pumps in operation.
• Pump changeover is automatic and
depends on load, operating hours and
fault.
• All pumps in operation run at the same
speed.
• The number of pumps in operation also
depends on the energy consumption of
the pumps. If only one pump is required,
two pumps will be running at a lower
speed if this results in a lower energy
consumption. This requires that the
differential pressure of the pump is
measured and pump curve data are
available for the controller.
6
Systems with pumps connected to
one CUE frequency converter
Control MPC-F
Control MPC with three pumps
connected to one Grundfos CUE
frequency converter. The speed-
controlled operation alternates between
the pumps.
One pump connected to a Grundfos
CUE frequency converter in operation.
H
H
set
Q
One pump connected to a Grundfos
CUE frequency converter and two
mains-operated pumps in operation.
H
H
set
Q
• Control MPC-F maintains a constant
pressure through continuous adjustment
of the speed of the pump connected to
the Grundfos CUE frequency converter.
The speed-controlled operation alternates
between the pumps.
• A pump connected to the Grundfos CUE
frequency converter always starts first. If
the pressure cannot be maintained by the
pump, one or two mains-operated pumps
will be cut in.
• Pump changeover is automatic and
depends on load, operating hours and
fault.
Systems with mains-operated pumps
Control MPC with three mains-operated
pumps.
PT
One mains-operated pump in operation.
H
stop
H
set
Q
Three mains-operated pumps in
operation.
H
stop
H
set
Q
• Control MPC-S maintains an almost
constant pressure through cutting in/out
the required number of pumps.
• The operating range of the pumps will lie
between H
(cut-out pressure).
• Pump changeover is automatic and
depends on load, operating hours and
fault.
Control MPC-S
PT
and H
set stop