Electrical Connection; Electrical Protection; Mains And Motor Connection - Grundfos CUE Series Installation And Operating Instructions Manual

6. Electrical connection

Warning
The owner or installer is responsible for ensuring
correct earthing and protection according to
national and local standards.
Warning
Before making any work on the CUE, the mains
supply and other voltage inputs must be
switched off for at least as long as stated in
section 3. Safety and warnings.
ELCB
Fig. 10 Example of three-phase mains connection of the CUE
with mains switch, back-up fuses and additional
protection

6.1 Electrical protection

6.1.1 Protection against electric shock, indirect contact
Warning
The CUE must be earthed correctly and protected
against indirect contact according to national
regulations.
The leakage current to earth exceeds 3.5 mA, and
Caution
a reinforced earth connection is required.
Protective conductors must always have a yellow/green (PE) or
yellow/green/blue (PEN) colour marking.
Instructions according to EN IEC 61800-5-1:
• The CUE must be stationary, installed permanently and
connected permanently to the mains supply.
• The earth connection must be carried out with duplicate
protective conductors.
6.1.2 Protection against short-circuit, fuses
The CUE and the supply system must be protected against short-
circuit.
Grundfos demands that the back-up fuses mentioned in section
16.6 are used for protection against short-circuit.
The CUE offers complete short-circuit protection in case of a
short-circuit on the motor output.
6.1.3 Additional protection
Caution The leakage current to earth exceeds 3.5 mA.
If the CUE is connected to an electrical installation where an
earth leakage circuit breaker (ELCB) is used as additional
protection, the circuit breaker must be of a type marked with the
following symbols:
The circuit breaker is type B.
The total leakage current of all the electrical equipment in the
installation must be taken into account.
The leakage current from the CUE in normal operation can be
seen in section 16.7.1 Mains supply (L1, L2, L3).
During start and in asymmetrical supply systems, the leakage
current can be higher than normal and may cause the ELCB to
trip.
6.1.4 Motor protection
The motor requires no external motor protection. The CUE
protects the motor against thermal overloading and blocking.
ELCB
6.1.5 Protection against overcurrent
The CUE has an internal overcurrent protection for overload
protection on the motor output.
6.1.6 Protection against mains voltage transients
The CUE is protected against mains voltage transients according
to EN 61800-3, second environment.

6.2 Mains and motor connection

The supply voltage and frequency are marked on the CUE
nameplate. Make sure that the CUE is suitable for the power
supply of the installation site.
6.2.1 Mains switch
A mains switch can be installed before the CUE according to local
regulations. See fig. 10.
6.2.2 Wiring diagram
The wires in the terminal box must be as short as possible.
Excepted from this is the earth conductor which must be so long
that it is the last one to be disconnected in case the cable is
inadvertently pulled out of the cable entry.
Fig. 11 Wiring diagram, three-phase mains connection
Terminal Function
91 (L1)
92 (L2) Three-phase supply
93 (L3)
95/99 (PE) Earth connection
96 (U)
Three-phase motor connection, 0-100 % of
97 (V)
mains voltage
98 (W)
6.2.3 Gland plate
Cables are connected through the gland plate from the bottom.
The gland plate must be fitted to the CUE to ensure the specified
protection degree as well as to ensure sufficient cooling.
Drill holes in the marked areas. See fig. 12.
Fig. 12 CUE viewed from the bottom
Mains
Motor
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