Installation
Grundfos CUE
32
The outlet from the ventilation must be placed above
the highest-mounted CUE. Allowance must be made for
the pressure loss across the inlet filters of the control
panel and for the fact that the pressure will drop as the
filters get choked.
Example: C
alculate the required air flow for cooling of
a built-in CUE when the ambient temperature is 80° F
(27 °C). The CUE has a typical shaft power of 11.0 kW
(ISHP) and an efficiency of 0.98. See page 44.
Calculate the power loss of the CUE:
P = P2 x efficiency = 11.0 x (1-0.98) x 1000= 220 W.
Calculate the required air flow for cooling the CUE:
q
v
= (P x 3.285) / (ΔT) = (220 x 3.285) / (131-80) =
14.2 ft
3
/min.
Electrical installation
Note: Always observe national and local regulations as
to cable cross-section, short circuit protection and over-
current when installing the CUE.
Fig. 38 Example of three-phase mains connection of the
CUE with mains switch, back-up fuses and addi-
tional protection
Electrical protection
Protection against electric shock, indirect contact
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
an
d connected permanently to the mains supply.
• The earth connection must be carried out with dupli-
cate protective conductors or with a single rein-
forced protective conductor with a cross-section of
mini
mum 8 AWG [10 mm
2
].
Protection against short-circuit, fuses
The CUE and the supply system must be protected
against short-circuit.
Grundfos demands that the fuses mentioned on 48 are
used for protection against short-circuit.
The CUE offers complete short-circuit protection in
case
of a short-circuit on the motor output.
Additional protection
Note: T
he leakage current to earth exceeds 3.5 A.
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.
Leakage current of the CUE in normal operation, see
pag
e 51.
During start and in asymmetrical supply systems, the
leaka
ge current can be higher than normal and may
cause the ELCB to trip.
Motor protection
The motor requires no external motor protection. The
C
UE protects the motor against thermal overloading
and blocking.
Protection against overcurrent
The CUE has an internal overcurrent protection for
over
load protection on the motor output.
Protection against mains voltage transients
The CUE is protected against mains voltage transients
accor
ding to EN 61800-3, second environment.
TM03 8525 1807
ELCB
ELCB
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