Increase of BMS cables sale
The global IBMS market
is highly fragmented with the presence of several global and local vendors.
Global vendors mostly operate as original equipment manufacturers (OEMs),
catering to the requirements of the end-user through distributors/dealers or
system integrators. Technical knowledge and ability to customize based on
end-user requirement by vendors will hold the key to a strong foothold in the
market.
Building management
system cables also commonly known as BMS cables, intelligent
building cables or automation cables are used to automate
all of the systems in place within a building or home. Research suggesting the
BMS market will reach $19.25 million by 2023; it’s even more of an opportunity
for electrical contractors to capitalize.
The global IBMS market will
continue to grow at a healthy pace throughout the forecast period. Apart from
energy and cost savings, other important drivers are the degree of flexibility
provided by open IBMS solutions, the high degree of productivity it provides,
and a higher return on investment along with enhanced security. These factors
are attractive to many businesses, thus driving the market growth.
An advance Building
Management System can control the safety in homes and offices, monitoring doors
and windows for alarm systems and detect floods and fires. Equipment and
installations are designed for the control, monitoring and optimization of
various functions and services provided in a building that includes: heating,
ventilation, air-conditioning, lighting, security systems and
the operation of electric / electronic applications.
A shielded
cable that is not grounded does not work effectively. Any
disruptions in the path can raise the impedance and lower the shielding effectiveness.
Firstly make sure you have a cable with sufficient shielding for
the application's needs. In moderately noisy environments, a foil alone
may provide adequate protection. screened cable (plural screened
cables) Wire for the transmission of electricity or electronic signals,
protected by an enclosing web of earthed wire mesh to avoid
electromagnetic interference from (or to) other signals. Grounding: a point in
contact with the ground, a common return in an electric circuit and a arbitrary
point of zero voltage potential. It also provides personal safety and protects
the equipment. Control the voltages developed on the ground when the
earth-phase short circuit returns through a near or distant source. Provide a
stable voltage reference to signals and circuits. Minimize Electromagnetic
Emission (EMI) effects.
Shielding: The shield must be connected to the signal
reference potential of what is being protected. When there are multiple
segments keep them connected, ensuring the same reference potential. The
shielding is only efficient when it establishes a low impedance path to the
ground. A floating shielding does not protect against interference. The use of
non-magnetic metals around conductors does not shield against magnetic fields.
The cabling of the industrial communication systems
(Modbus RS485) is different in some ways from the cabling used for power
cabling and the electrician may experience some difficulties if he is not
an expert in Modbus communication networks. A Modbus RS485 connects a
Master device to one or more Slave devices. Henceforth, we shall consider Slave
devices to be measuring instruments with serial communication, even if the
cabling is similar for all Modbus devices.
Cable Selection
You should consider the following:
·
How many conductors do you need?
A minimum of three conductors, but the shield may be used
as the common conductor, so shielded two conductor cable may be used. If you do
not use shielded cable, then at least three conductors are required. Some
RS-485 devices do not use a common connection, but we recommend always
connecting common for reliable performance and to avoid damage due to surges.
·
What wire gauge do you need?
·
For unterminated networks,
the current will generally be less than 10 mA and any gauge should work; we
recommend #24 AWG to 18 AWG.
·
For terminated networks, the current
can be 60 mA or higher, so heavier gauge wire may be needed for very long runs.
·
We recommend #22 to #20 AWG for runs up to 1000
ft. (~300 m).
·
We recommend #20 to #16 AWG for runs up to 4000
ft.(~1200 m).
·
What should the cable impedance and
capacitance be?
Cables suitable for use in an RS-485 network should have
an impedance of between 100 and 130 ohms, a capacitance between conductors of
less than 30 pF per foot (100 pF per meter), and a capacitance between
conductors and shield less than 60 pF per foot (200 pF per meter).
·
Do you need shielding?
Because RS-485 is differential, it is less susceptible to
interference, so shielding is not always necessary. However, we recommend
shielding for long runs and if there is electrically noisy equipment nearby
like variable speed drives. If you use shielded cable, connect the shield to
earth ground at one end (generally the PC or RS-485 master).
·
Do you need twisted wires?
Yes, especially for non-shielded cable.
·
What voltage rating do you need?
We recommend wire or cable rated for the highest voltage
present. So if you are monitoring a 120/208 Vac panel, you should use 300 V
rated cable. If you are monitoring a 480Y/277 volt circuit, use 600 V rated
cable. If you have the WattNode in a separate enclosure and there is no way the
mains wires can contact the Modbus output cable, then you could safely use
lower voltage rated cable, such as 150 V or lower. Long runs of 300 V or 600 V
rated cable may be expensive, so it may be more economical to use lower voltage
rated cable and use a protective jacket in the regions where the cable is in
the vicinity of dangerous voltages.
·
Can you run the RS-485 network cable adjacent
to or in the same conduit with mains wires?
We strongly recommend against this. There
may be interference from the high voltages and currents present on the mains
wires, and if there is any insulation fault, arcing, etc. on the mains wires,
it could put dangerous voltages on the low-voltage RS-485 network cable.
Most modern buildings
now incorporate some form of BMS, focusing primarily on energy efficiency and
saving costs. Whether that’s through proximity sensor lighting, climate
control, door entry or security, they all work to achieve the same goal.
Efficient lighting control in a BMS system is just one
way of reducing energy and saving costs for building owners. Using BMS,
lighting can be automatically adjusted, depending on natural light detected or
amount of people in the building. These cables are available in Low Smoke
Halogen Free (LSHF), meaning they give off minimal smoke and toxic fumes. This
is ideal for installation in public buildings such as schools, hospitals or airports
where evacuation may be difficult in the event of a fire.
Unlike what happens in many energy distribution systems,
the manner in which the devices are connected in parallel is important.
The RS-485 system used for Modbus communication provides a main cable (Bus
or backbone), to which all the devices have to be connected with branches
(also known as stubs) that are as short as possible. The branches must be
no longer than 1200 mtr.
Maximum distance and maximum number of devices. The main
cable must be no longer than 700 m! This distance does not include
the branches (which must nevertheless be short). The maximum number of
devices that can be connected to a main cable is 32, including the
Master.
In order to increase the extent of the Modbus
network, repeaters can be used; and signal amplifying and
regenerating devices provided with two communication ports that transfer
to each what they receive from the other.
The cable shield must be earthed only in one point.
Normally, this connection is made at one end of the main cable.
In order to avoid signal reflections, a 120 Ohm termination
resistance must be fitted on each end of the main cable. The end
resistance must be used only at the ends
of the main cable. If the total length of the main cable
is less than 50 m termination resistances can be avoided at the
ends of the main cable.
Fire safety is another major reason why owners may
consider installing a BMS system into their building. High performance fire
survival cables provide an excellent solution for connecting BMS with fire
systems. The data and coaxial ranges are designed to carry on functioning in
the event of a fire and provide vital signals to voice alarm, CCTV and allow
systems to be shut down in an orderly fashion. Meeting specific fire resistance
requirements.
