Dry-Run Protection; Technical Details - Wilo Sub TWU 3 Série Notice De Montage Et De Mise En Service

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5 Connect the discharge pipe to the discharge port. A
seal must be placed between the flanges of the pipe-
line and the unit. Tighten the fastening bolts in a cross
pattern to avoid damaging the seal. Please note that
the pipe system is mounted so that there is no vibra-
tion or tension (use elastic connection pieces, when
necessary).
6 Lay the cables in such a manner that no-one (mainte-
nance personnel etc.) will be endangered by them at
any time (operation, quick repairs). Do not damage the
power supply lines. The electrical connection must be
carried out by an authorized technician.
5.4.4 Inserting the Plug&Pump systems
Fig. 4: Installation
1 Unit
2 Motor connection cable
3 Holding cable
4 Screw connection 1¼"
5 Screw connection 1"
6 Fluid control
* Kit pre-assembled at the factory, consisting of:
• 18 l diaphragm pressure vessel
• Pressure manometer
• Shut-off valve
TWU...-P&P/FC (Economy 1)
For fixed pipes or flexible hose connections with 1¼"
nominal width (40 mm diameter).
In case of hose connections, the supplied union nuts
are used. These are installed as follows:
• Loosen the bolted connection and leave it in place on
the thread whilst inserting the hose.
• Push the hose through the bolted connection up to the
stop.
• Tighten the bolted connection using the pipe wrench.
In case of a fixed pipe connection, the supplied 1¼"
union nut is used for the pump/pipe connection and
the 1¼" x 1" reducer for connecting to the fluid con-
trol.
TWU...P&P/DS (Economy 2)
For fixed pipes with 1¼" nominal width (40 mm diame-
ter).
The system is pre-assembled. Only the T-piece needs
to be attached to the assembly.
Please ensure that the support on the pressure
manometer is set to the highest position!

5.5 Dry-run protection

Make sure that no air enters the hydraulic housing. The
product must therefore always be submerged in the
pumped liquid up to the top edge of the pump hous-
ing. For optimum reliability, we recommend installing a
dry-run protection system.
34
7 Mains supply
8 Pressure switching kit*
9 T-piece
Filling valve for dia-
10
phragm pressure vessel
Supports on pressure
11
manometer
Correct running is ensured by float switches or elec-
trodes. The float switch or electrode is fixed in the
shaft and switches off the machine when the water
level falls below the minimum coverage level. If the dry-
run protection is put into effect with only one float or
electrode whilst the filling levels fluctuate strongly,
there is a danger that the unit will turn on and off con-
stantly!
This can result in the maximum number of motor
start-ups (switching cycles) being exceeded and
the motor overheating.
5.5.1 Corrective measures for avoiding excessive switch-
ing cycles
Manual reset - The motor is switched off when the
water level falls below the minimum coverage level and
switched back on when a sufficient water level is
reached.
Separate reactivation point - A second switching
point (additional float or electrode) is used to obtain a
sufficient difference between the activation and deac-
tivation points. This prevents constant switching. This
function can be put into effect with a level control
relay.
5.6 Electrical connection
Risk of fatal injury due to electrical current!
There is a risk of fatal electric shocks caused by
improper electrical connections. Electrical con-
nections may only be carried out by a qualified
electrician who is approved by the local power
supplier, in accordance with locally applicable
regulations.
• Mains current and voltage must correspond to the
details on the type plate.
• Connect the power supply cable in accordance with
the applicable standards and regulations and accord-
ing to the wire assignment.
• Any available monitoring equipment, e.g. for the motor
temperature, must be connected and tested to ensure
that it is working properly.
• For three-phase current motors, a clockwise rotating
field must be available.
• Ground the product properly.
Products that are permanently installed must be
grounded in compliance with nationally applicable
standards. If a separate grounding conductor is avail-
able, it must be connected to the marked hole or
grounding terminal ( ) using a suitable screw, nut,
toothed washer and flat washer. The cross section of
the cable for the grounding conductor connection
must correspond to the local regulations.
• A motor protection switch must be used. We recom-
mend using an earth leakage circuit breaker (RCD)
• Switching devices are to be purchased as accessories.

5.6.1 Technical details

• Activation type: Direct
• Power supply fuse: 10 A
• Cable cross section 4 x 1.5
Only slow-blow fuses or K characteristic automatic
cut-outs may be used for pre-fusing.
WILO SE 10/2011 V4.1WE