Showing posts with label 18 AWG. Show all posts
Showing posts with label 18 AWG. Show all posts

Monday, November 11, 2019

Increase of BMS cables sale

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.