Servicing The Product; Differential-Pressure And Temperature Sensor; External Sensor Condition; Disassembling The Plug - Grundfos MAGNA3 25-80 Installation And Operating Instructions Manual

9. Servicing the product

Before dismantling
WARNING
Electric shock
Death or serious personal injury
- Make sure that other pumps or sources do not
force flow through the pump even if the pump is
stopped. This will cause the motor to act like a
generator, resulting in voltage on the pump.
WARNING
Electric shock
Death or serious personal injury
- Switch off the power supply for at least 3 minutes
before you start any work on the product.
- Lock the main switch in position 0. Type and
requirements as specified in EN 60204-1, 5.3.2.
WARNING
Magnetic field
Death or serious personal injury
- Persons with pacemakers disassembling this
product must exercise care when handling the
magnetic materials embedded in the rotor.

9.1 Differential-pressure and temperature sensor

The pump incorporates a differential-pressure and temperature
sensor. The sensor is located in the pump housing in a channel
between the inlet and outlet ports. The sensors of twin-head
pumps are connected to the same channel and the pumps
therefore register the same differential pressure and temperature.
Via a cable, the sensor sends an electrical signal for the
differential pressure across the pump and for the liquid
temperature to the controller in the control box.
If the sensor fails, the pump continues using the last
measurement from the sensor and operate based on this. In
earlier software versions, model A, the pump runs at maximum
speed in case of a sensor fault.
When the fault has been corrected, the pump continues operating
according to the parameters set.
The differential-pressure and temperature sensor offers
substantial benefits:
• direct feedback on the pump display
• complete pump control
• measurement of the pump load for precise and optimum
control resulting in higher energy efficiency.

9.2 External sensor condition

In case of missing sensor signal:
• Pumps produced before week 4, 2016: The pump runs at
maximum speed.
• Pumps produced after week 4, 2016: The pump runs at 50 %
of the nominal speed.
50

9.3 Disassembling the plug

Step Action
Loosen the cable
1 gland and remove it
from the plug.
Pull off the plug
2 cover while pressing
on both sides.
Loosen the cable
conductors one by
3 one by pressing a
screwdriver gently
into the terminal clip.
The plug has now
been removed from
4
the power supply
plug.
Illustration
Max 0.8 x 4
x 3