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4LPPT70EN - 5/2023
2.3 Electrical equipment
Standard electrical equipment includes the following unless
the pump is equipped with a vacuum assistant:
• hose leak detector
Optional electrical equipment can include the following:
• control cabinet
• pressure transmitter with display and overpressure limit
• revolution detector
• revolution counter and speed display (without wiring or
box)
The control centre unit controls LPP-T pumps. The unit
includes the following:
• frequency inverter
• required safety equipment
• reversing switch in stopping position
• fuses
• the possibility of connecting hose leak, overpressure, and
revolution detectors
The electric motor can be operated with local speed control
(potentiometer) connected to the control cabinet, or with
remote control (4–20 mA or 0–10 V) using a control signal.
The
control cabinet
can be installed in connection with
the pump or as a separate unit. If the control cabinet is
delivered as a separate unit, it must be connected by a person
authorised to perform electrical connections.
The
pressure transmitter
, which operates with a voltage
of 24 V, is equipped with a display and a programmable
overpressure relay. It can be connected to the drive circuit
of the control cabinet with a pilot wire. If the programmed
pressure value is exceeded, the control cabinet stops the
pump automatically. The transmitter can be programmed
directly with the buttons on the transmitter. After stopping,
the pump can be restarted only through pressing of the
acknowledgement button.
WARNING!
Electrocution hazard. All electrification connections
must be made by professionals only.
The
hose leak detector
is installed outside the pump housing,
on the back wall. The detector is a two-wire, float-type
switch connected to the pump’s drive circuit. If the hose is
punctured, the pumped medium starts leaking into the pump
housing. When the surface of the liquid reaches the hose leak
detector, the detector stops the rotation of the pump. Detector
needs to be connected to a VFD or control cabinet.
If the detector is connected to a control cabinet supplied by
Valmet Flow Control, the acknowledgement button must
be pressed after a hose puncture. The pump can be restarted
only after the button is pressed.
The
revolution detector
is an inductive sensor to be
installed at the rear wall of the pump. It sends an impulse
for each crankshaft rotation detected. The sensor requires an
operating voltage of +24 V.
The revolution counter and/or speed display are installed on
the door of the control cabinet. To operate, the counter and
display require a power supply and the pulse data from the
revolution detector. The counter is equipped with battery
backup in case of power failure.