CYME
Power Engineering Software and Solutions
Identify the right type of cable for
your low voltage installation
The low voltage cables are those
with a voltage rating equal or
less than 1kV. The sizing of low
voltage cable covers most of
the common non-armored cable
installations for utility, domestic,
commercial and industrial
systems. It is not suitable for
distribution feeders.
Different installations require
different cable design and
materials. The CYME Low
Voltage Cable Sizing module
calculates the cable size at a
given location on the network
according to any one of the
following standards:
•
IEC 60364© 5-52 standard:
Low-voltage electrical
installations – Part 5-52:
Selection and erection of
electrical equipment – Wiring
systems.
•
NEC methodology: NFPA-
70-2011© National Electricity
Code.
Specifically, the module
handles systems 3-phase or
single-phase systems that
are radial and balanced. The
conductor materials supported
by the calculations are copper or
aluminum, while the insulation
or cable types are as per the
standards.
Low voltage cables are
widely used in utility and
industrial installations
requiring AC voltages of
1 kV or less. Being able to
select the proper cables
based on clear criteria is key
to ensure that the installation
is safe and that the cables
will operate reliably for their
expected service time.
The CYME Low Voltage
Cable Sizing module helps
the power engineer do that
selection while designing
an installation, and simulate
various operating conditions
and cable loading.
Low Voltage Cable Sizing
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Printed in Canada
Publication No. BR 917 072 EN
March 2017
Low Voltage
Cable Sizing
Identify the right type of
cable for your low voltage
installation
Calculations
The calculations takes into
account conductor material,
insulation material and
manufacturer:
•
Ampacity level – taking
into account the installation
method of the cable, the
software determines the cable
size for the installed ampacity.
It is executed based on factors
that include the soil thermal
resistivity and temperature
along with the grouping of the
circuits.
•
Voltage drop limit during
normal operating conditions –
executed based on standard
voltage drop formula. The
software determines the
cable size for the voltage drop
constraints specified. It takes
into account the resistance,
the reactance and the length
of the cable; and provides data
on the maximum voltage drop
allowed.
•
Short-circuit withstand
capability (IEC only) –
calculates the short-circuit
temperature rise based on
the maximum fault current
and fault duration, either
user-defined or based on
the short-circuit analysis just
performed .
•
When more than one
calculation is performed for
one installation, the software
will determine an optimal size
and will suggest a specific
cable from the cable library of
the software.
•
The full load current and
power factors can be based
on a load flow analysis just
performed or can be defined
by the user.
Vast cable library
A key element in sizing
cables is the cable type. The
CYME software includes a
comprehensive cable library that
comprises a large number of
low voltage cables from various
manufacturers. These include
one-core, three-core and three-
core with ground conductor
with all the nominal and cable
construction data available for
the calculations.