Grundfos CONTROL MPC Installation And Operating Instructions Manual page 7

8. Overview of control variants
The examples below are based on booster systems.
Systems with speed-controlled
pumps
Control MPC-E
Control MPC with three E-pumps.
PT
One E-pump in operation.
H
H
set
Three E-pumps in operation.
H
H
set
• Control MPC-E 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 will run at equal
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.
Systems with pumps connected to
one CUE frequency converter
Control MPC-F
Control MPC with three pumps
connected to an external Grundfos CUE
frequency converter in the control
cabinet. The speed-controlled operation
alternates between the pumps.
One pump connected to an external
Grundfos CUE frequency converter in
operation.
H
H
set
Q
One pump connected to an external
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
external Grundfos CUE frequency
converter. The speed-controlled operation
alternates between the pumps.
• One pump connected to the external
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
H
stop
H
set
Q
Three mains-operated pumps in
operation.
H
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
• Pump changeover is automatic and
depends on load, operating hours and
fault.
Control MPC-S
PT
Q
Q
and H (cut-out pressure).
set stop
7