Dry-Running Protection; Electrical Connection; Technical Information - Wilo Sub TWU 3 HS Serie Notice De Montage Et De Mise En Service

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5.3.4 Installing an external frequency converter
Fig. 4: Description
1 Inlet
2 Pressure connection
The frequency converter is installed directly in
the piping so that it is cooled by the fluid being
pumped during operation.
Note:
• Ambient conditions:
• Ambient temperature: 4...40 °C (frost-proof)
• Fluid temperature: 3...35 °C
• Protection class: IPX5 (overflow-proof instal-
lation).
• The electrical connection and all settings are
carried out on the frequency converter itself. It
therefore needs to be easily accessible.
• During installation, note the direction of flow.
See the direction of flow arrow on the frequency
converter's housing.
NOTE:
The pressure and inlet connection on the
frequency converter is sized G 11/4, the pres-
sure connection on the pump is sized Rp 1 for
version TWU 3-05..-ECP Rp 1¼. Depending on
the discharge pipeline, 1 or 2 adaptors need
to be installed downstream of the frequency
converter by the customer.

5.4 Dry-running protection

Submersible pumps are cooled by the fluid.
Therefore, the motor must always be immersed.
In addition, make sure that no air enters the
hydraulics housing. The pump must therefore al-
ways be immersed in the fluid up to the top edge
of the hydraulic housing. For optimum operational
reliability, we recommend installing a dry-running
protection system.
The TWU 3-...-HS has a built-in dry-running pro-
tection in the frequency converter. If the water
level fluctuates strongly, the motor's maximum
switching cycles may be exceeded. This could
lead to overheating of the motor. In this case, we
therefore recommend an additional dry-running
protection provided by the customer.
Dry-running protection is provided with the help
of electrodes or level sensors. The signal trans-
mitter is fixed in the borehole/basin and switches
off the pump when the water level falls below the
minimum water submersion.
5.4.1 Remedies for avoiding excessive switching
cycles
Manual reset – the motor is switched off when
the water level falls below the minimum cover-
age level and switched back on when a sufficient
water level is reached.
Separate reactivation point – a second switch-
ing point (additional electrode) is used to obtain
a sufficient difference between the activation
40
3 Direction of flow arrow
and deactivation points. This prevents constant
switching. This function can be put into effect
with a level control relay.

5.5 Electrical connection

RISK of death due to electrocution!
Incorrect electrical connections can cause fa-
tal electric shocks. Electrical connections may
only be carried out by a qualified electrician
approved by the local energy supply company,
in accordance with locally applicable regula-
tions.
• The mains connection current and voltage must
be as stated on the rating plate.
• Connect the power supply cable in accordance
with the applicable standards and regulations and
according to the conductor assignment.
• Any available monitoring equipment must be
connected and tested to ensure that it is working
properly.
• Earth the submersible pump according to the
regulations.
Units that are permanently installed must be
grounded in compliance with nationally appli-
cable standards. If a separate protective earth
conductor is available, it must be connected
to the marked drilled hole or earth terminal (;)
using a suitable screw, nut, toothed washer and
flat washer. The cross-section of the cable for
the protective earth conductor connection must
comply with local regulations.
• A power supply separator (main switch) must be
provided by the customer!
• We recommend using a residual-current de-
vice (RCD).
• Switchgears must be purchased as accessories.

5.5.1 Technical information

• Activation type: Direct
• Fuse on mains side: 16 A
• Cable cross-section, pump/frequency converter:
• Up to 30 m: 1.5 mm²
• From 30...90 m: 2.5 mm²
• Cable cross-section, power supply separator/fre-
quency converter:
• Up to 1.1 kW: 1.5 mm²
• from 1.2 kW: 2.5 mm²
• With cable lengths of 5 m or more, always use
a cable cross-section of 2.5 mm² in order to
avoid any interference due to voltage drop.
• Temperature resistance of the cable: max. 75 °C
• Only slow-blow fuses or K-type circuit breakers
may be used as a back-up fuse.
5.5.2 Unit with built-in frequency converter
(TWU 3-...-HS-I)
The version with built-in frequency converter is
delivered ex works with a connected power sup-
ply cable. This cable has to be extended, accord-
ing to the available space in the borehole, using
heat-shrink tubing or a cast resin connection, by
the customer before installation.
INSTALLATION
WILO SE 05-2019 DIN A4