Tech View

Making electrical systems smarter and safer

The article illustrates the need to equip electrical facilities with the latest technologies and innovations.

With speeding electrification across India and strong government focus on the power sector, we are now in an era where having a lighted house is not the privilege of a few anymore. However, it is our responsibility to make power safe and secure for everyone.

According to the National Crime Records Bureau, in India nearly 10,000 accidental deaths happen each year due to exposure to dangerous levels of electricity. An analysis of the incidents brings up the major ways through which these incidents have happened.

Electrocution by high tension wire
The most common reason behind fatal incidents is coming in contact with live HT wire. Many labourers have lost their life in factories where tall aluminium ladders have touched overhead wires. Other incident reports the balcony of a house was extended to dangerous level where a sagging overhead live transmission wire was touched by kids and they were electrocuted. During monsoons, current may transmit through water which comes in contact with a HT wire. Surprisingly, electricity theft has also been a contributor where someone trying to cut a live wire got electrocuted!

Building fire due to short circuits
Several incidents have been reported where a short circuit in building electric network has created fire due to local overheating of insulation and also presence of combustible material in the path of electric spark. Mechanic strain, high temperature, and evaporation of softeners from PVC insulation make the wire porous. Even the smallest creeping current makes the facility vulnerable of huge fires.

Electric shocks in household environment
While we operate at 415V line voltage in our houses, the usage of heavy-duty appliances like air-conditioners, water heaters and electric motors make us equally prone to risk with currents as high as 500 mA which is fatal even in short exposure times. Presence of leakage currents, ground faults and unbalanced phase can bring damages of different intensity.

Here is a brief about 3-stage protection concept of electricity:
The major electrical equipment like bus bars, links, transformer, motor, generator and capacitor banks are susceptible to failures like short circuits, overloads, earth fault, residual current and arc fault. Important switchgears for their protection are relays, circuit breakers, contactors, residual current devices, sensors and monitoring devices. With proper co-ordination and time settings, the power systems are designed to minimise downtime and reduce risk.

Most of the protection devices available today in market are equipped with the basic design and operational principle. However, we must equip our electrical facility with the latest technologies and innovations brought up by the cutting-edge products and solutions, with proven performances and high resolutional efficiency. A look through some of these advances is detailed in the below section.

Miniature circuit breakers
Eaton’s MCB comes with 3 position mounting clip for quick and easy maintenance, which allows installation and removal without removing the busbar. It has insulated sliding shutter for safe and secure termination. It comes with a true contact position indicator rather than a mechanical one which trips by the movement of the dolly. Equipped with bi connect terminals, it allows secure termination of busbars and cables simultaneously. These MCBs offer different colour coding for different amp rating of the breaker which makes it easy for service personnel to identify and distinguish between different ratings of breakers. With the provision for remote operation, electrical systems can significantly reduce their maintenance and repair time as the person need not be physically present at the sight for a quick on and off operation.

Digital residual current devices
The Digital RCDs make troubleshooting faster and much easier as compared to the conventional RCDs present in the market. The LEDs present on these devices set off an alarm when fault currents or a shutdown is coming. This makes the service mode of the fault current protection switch quickly indicate the extent of the flowing fault current in milliamp increments. By pushing the service button, the blinking LED identifies the area where the fault current is located in.

With Eaton’s dRCM
Residual current protection which is mains voltage-independent, additional protection with other digital functions and Auto-reclosure is possible. Different colour LEDs are mounted to indicate the level of leakage current and Operational response.

When the red LED lights up, the leakage current is already higher than 50 per cent of the nominal fault current. Therefore the system is in a critical status –the digital RCCB only trip when the fault current continues to increase.

The yellow LED shows a residual current in the ambit of 30 to 50 per cent of the nominal fault current. Before the system is shut down, professional countermeasures can be taken.

If the current flow in the system to ground is in the ambit from 0 to 30 per cent of the nominal fault current, the green LED indicates the proper status.

Connectivity solutions & industrial automation
With the “Make In India” initiative and multinationals building their base production lines in India, industrial automation is the next big thing. We need to look beyond the acquisition cost of basic industrial switchgears and consider the operational and downtime cost. Production line downtime may incur heavy losses, much more than the cost of solutions which promises and delivers uptime. Also, lives of many labourers are at risk in the large factories and industries. A safe and clean production line reciprocates in quality of the products made.

While the new technology Smart Wire DT from Eaton reduces trouble-shoot time, it also adds to the aesthetics and clarity in complex circuits.

The SmartWire-DT system uses a continuous green flat cable located in the control cabinet to connect motor starters, pushbutton actuators, and indicator lights. It eliminates the need for most of the conventional point-to-point control wiring and even integrates 24 V DC control power for contactor coils on the eight conductor flat cable.

The start of the SmartWire-DT system is a gateway. It establishes the connection to standard programmable logic controller (PLC) fieldbuses. Because SmartWire-DT directly integrates the input/output (I/O) level in the switching devices, no conventional PLC I/O modules are needed. Instead communication enabled modules are attached to standard Eaton motor control components. Thus, the PLC in the control cabinet simply consists of a central processing unit (CPU) module. Typical faults such as loose connections and miswired terminations are eliminated using the flat cable and the specialised connectors.

Furthermore, each SmartWire-DT enabled device has individual diagnostic LEDs built in, which reduce commissioning time and troubleshooting in the field. Nodes on the SmartWire-DT network are automatically assigned addresses on the gateway with the push of a button—assigning addresses in the order that the nodes are connected. The system employs time monitoring and a watchdog timeout using the established target configuration as a reference—safely monitoring the integrity of the control scheme. Smart Wire-DT has a maximum network length of 2000 ft, can be extended to pushbutton control stations outside of the control cabinet, and can connect up to 99 nodes per gateway. A software program called SWD-Assist enables the layout, planning, and system configuration of a SmartWire-DT network.

Adapting our electrical set up to latest technology can help us mitigate varied errors which might be risky for an industry or an individual. Along with the basic design, add on features as those present with Eaton can help safety and reliability reflect in complex environments.

Authored by:
Pallavi Sinha
Prescription Manager- South India
Eaton – Electrical Sector

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