HT and LT wires call for increased quality testing and inspection

The high-tension (HT) and low-tension (LT) wire market is growing in India with better quality products and improved safety standards that necessitate greater testing and third-party inspections to ensure that the market is safeguarded against spurious quality and poor competition. Industry players present their views on how they are working towards these goals and what can be done to improve the market’s status quo.

The insulated wire and cable market in India is expected to grow at a CAGR of 10.3 percent through 2023, predominantly on account of growing government investments towards infrastructure development projects. Development of smart cities across the country under the Smart Cities Mission coupled with increasing number of electronic devices per household and development of manufacturing industries under the “Make in India” initiative, which is driving demand for power, are expected to boost market demand in the coming years. Moreover, growing demand for reliable and efficient energy and data communication from rural areas and tier II and tier III cities and towns would positively influence the country’s insulated wire and cable market.

HT and LT wires

High-tension (HT) wires have PVC or XLPE insulation of voltage grade up to 3.3 kV conforming to various Indian and international standard specifications. HT XLPE wires, i.e., cross linked poly-ethylene insulated wires offer extraordinary strength to withstand high voltages and are used as HT wires for underground voltage transmission systems. These wires are used in overhead transmission. XLPE insulated wires have better electrical, mechanical and thermal properties along with being lightweight.

Low-tension (LT) wires have PVC or XLPE insulation of voltage conforming to various Indian and international standard specifications. Cross-linked polyethylene (XLPE) means vulcanised polyethylene whose basic material is low-density polyethylene. Polyethylene is a thermoplastic material consisting of long-chain hydrocarbon molecules. At elevated temperatures, these molecules tend to move relatively to one another so that the material becomes increasingly deformable and will eventually melt at a temperature around 110°C. By means of a process similar to the vulcanisation of rubber, the polyethylene molecules can be cross-linked. The process of cross-linking or vulcanisation consists of producing chemical bonds at intervals between the long molecular chain to give a “ladder” effect which prevents slippage between molecules.

Quality, cost and excessive competition pose challenges

Deepak Talware, Regional Manager, KEC Intl Ltd (RPG Cables) states, “As a wire and cable unit, we are trying to achieve better quality, for which we are importing more German machines and are pushing for Make in India. Among raw materials and internal materials, copper and aluminium constitute a major chunk of the market, contributing around 45-50 percent. Copper and aluminium are non-ferrous metals and are manufactured by companies like MALCO Energy Limited, NALCO, Hindalco and so on. There are certain imports also, but prices are driven by the London Metal Exchange (LME) which fluctuates every day. That is one of the main challenges.”

Naman Singhal, Director, Prime Cable Industries Pvt. Ltd. says, “Another thing is that the electrical industry is very competitive. In the wires and cables sector, there are unorganised and organised players. But you will find that very few wire companies are organised. The challenges in the high-tension (HT) and low-tension (LT) wires segment are the quality and price differences that manufacturers face. Some vendors quote 20-30 percent less as they provide lower quality, and as a manufacturer, we know that such low costs cannot be achieved. There should be more quality barriers that the government needs to set in place. Stricter inspections need to be made. Third-party inspection must also be done. Samples must be sent to third-party inspectors so that quality can be crosschecked.”

Talware says, “In the wires and cables sector, the challenges that we are facing currently is pricing because in this particular sector, the major costs are raw material costs, which contribute almost 70-80 percent of the total selling guide.”

Also while talking about challenges, Shreegopal Kabra, Managing Director, RR Kabel says, “Dealing with fire is a big challenge in India. Between 2001 and 2014, 3,50,000 people died due to fire, i.e., an average of 52 people dying every other day due to fire. Around 85 percent fires are caused due to electricity failure. Out of this 85 percent, almost 70-80 percent is because of short circuit, be it anywhere in the world. The major reason of short circuit fire is PVC wire.” When a fire happens, PVC creates a high amount of black toxic smoke. Because of the dense smoke, there is no visibility. People caught in such hazardous situation fall helpless, having no clue how to exit or escape.

He adds, “Ideally, PVC should be banned in the wire industry. I understand that it can’t be banned immediately, but at least the government should make it mandatory to have an inspection done in all the commercial buildings, restaurants, shopping malls, etc. where the population is more and the density is greater. The government should keep a check so that when an incident happens, the density of smoke is almost zero.”

So, that is a challenge which the wires and cables sector has seen. Moreover, it is a very competitive market and working capital also has to be managed effectively because a lot of costly raw materials are required. If companies maintain the ratio in the FG and sale, then at least they can get a good margin and run their business.

Need for proper testing for better quality

Adequate testing needs to be done to ensure that the HT and LT wires introduced in the market are of high quality and meet the industry specifications. The following tests are good starting points for any manufacturer to undertake:

Earth resistance test

In any overhead or underground network, the earth resistance at any point along the length of a LV feeder is to have a maximum resistance of 10 ohms prior to connection to the existing network. In any overhead or underground network, the overall resistance to earth shall be less than 1 ohm prior to connection to the existing network.

HV test on XLPE wires already in service or previously energised

Except for new wires, testing at voltage higher than 5.0 kV is not permitted. Studies carried out on DC high-voltage testing of XLPE wires now conclude that:

DC testing above 5 kV of field aged XLPE wires generally increases water tree growth and reduces service life.

5 kV is not considered a “High-voltage DC Test”. The test voltages for tests on XLPE wires is now limited to 5 kV after in-service repairs and 10 kV for new installations.

A 5 kV Megger is suitable for a 5 kV test on wires after repairs.

The changes to this section will also make it possible for a repaired wire to be tested by repair crews and made available for immediate return to service.

HV test on new XLPE wires

Prior to the performance of this test, the screen wires must be connected to the permanent earth position. The wire shall be tested at the test voltage. If further repair works are undertaken and they require additional joints to be installed, the complete HV testing procedure shall be repeated.

Alternative HV test requirement on insulation of 11 kV wires

Where it is not practical to conduct a high-voltage test, the test requirements for insulation (core to screen wire) may be limited to testing for the condition of “safe to energise”. The following list of circumstances and conditions must be met as a minimum requirement:

The circuit voltage shall be 11 kV.

The circuit outage duration shall be not more than 48 hours.

The work shall involve extending or repairs to existing circuits.

The insulation test shall be applied for 1 minute between each phase core and screen with a 1,000 Volt minimum insulation tester (Megger).

Typically, the test result should be in the order of 1,000 meg-ohms.

Paper insulated wires:

Tests on LV wires

An insulation resistance test shall be conducted with a 1,000 Volt Megger. Test results as low as 10 meg-ohms on old wire circuits are common and therefore considered safe to energise.

Test on 11 kV and 33 kV wires between cores and earth

For three core belted wires, the test on any core shall be conducted between the core and lead sheath with the remaining two cores connected to earth.

Thus, it is seen that regular testing and inspections are crucial to ensure higher quality of products and also balance the competition in the market, so that good wire manufacturers are rewarded for their efforts and low-quality wires are weeded out from the market. A focus on wire quality is necessary not only for improved quality, but also securing the safety and trust of consumers which will propel the Indian wire sector to greater heights.

As a wire and cable unit, we are trying to achieve better quality, for which we are importing more German machines and are pushing for Make in India.
Deepak Talware, Regional Manager, KEC Intl Ltd (RPG Cables)

There should be more quality barriers that the government needs to set in place. Stricter inspections need to be made.
Naman Singhal, Director, Prime Cable Industries Pvt. Ltd.

Out of this 85 percent, almost 70-80 percent is because of short circuit, be it anywhere in the world. The major reason of short circuit fire is PVC wire.
Shreegopal Kabra, Managing Director, RR Kabel