Installed Power, Energy Use and Electrical Supply: Reading the Power Lines on a Textile Machinery Spec Sheet

Installed power is a sizing number

Installed (or connected, or rated) power in kW sums the nameplate ratings of drives, fans, heaters, pumps and auxiliary motors. Your electrician needs it to size cable, protection and transformer capacity. It says little about energy cost, for three reasons:

1. Motors rarely run at full rating. The US Department of Energy notes that most motors are designed to operate between 50% and 100% of rated load, with best efficiency usually near 75% (US DOE).
2. Not everything runs at once. Doffing motors, tube loaders, cleaning travellers and heaters cycle on and off.
3. Some loads are missing. Central suction, compressed air, humidification and lighting are often supplied by the mill and do not appear at all.

Lower installed power does not mean cheaper running; a higher figure may just mean more generous motor margins. Installed power also depends on configuration: a rotor spinner such as the RFRS30D is described as modular with up to 600 positions, so the figure for a short machine says little about a full-length one. Compare configurations, not model names.

Ask for measured consumption, with the conditions attached

What you want is specific energy consumption: kWh per kilogram of product (spinning, winding, texturing), or kWh per hour or per 1,000 m at a stated speed (weaving, knitting, finishing ranges). A number on its own is meaningless; ask the supplier to state:

• the product (count, fibre, fabric construction or weight) and machine speed;
• what was included (main drives only, or the machine's own fans, heaters and auxiliaries) and what was excluded (central suction, compressed air, air conditioning);
• how it was measured: a power analyser or energy meter at the machine's incoming supply over a production run, not a calculation from motor ratings;
• run duration and efficiency (the share of time producing).

Speed needs care: the ZXJP919 finishing line, for example, publishes a 100 m/min mechanical maximum separately from a 10–90 m/min process range, and energy per metre differs across that range.

The DOE describes the basic field method: measure line voltage, current and power factor on all three phases and calculate input power from them, or read it directly from a power meter (US DOE). Add a metered run with your own material to the factory acceptance test, and repeat it at site acceptance.

Voltage and frequency: China builds for 380 V, 50 Hz

China's national standard for supply voltages, GB/T 156-2017, covers 50 Hz systems only and lists 220/380 V for three-phase low-voltage distribution, where IEC 60038 gives 230/400 V (GB/T 156-2017, English edition). Chinese-built machines are therefore normally wired and tested at 380 V, 50 Hz unless you order otherwise.

Your site may differ. Many 50 Hz markets distribute at 400 V or 415 V, and US Motors' tables pair 380, 400 and 415 V at 50 Hz with 460 V motors at 60 Hz, alongside 230 V and 575 V classes (US Motors). Do not rely on a country table: obtain your actual site voltage, frequency, tolerance band and earthing system from your electrician or utility, and send it to the supplier in writing.

A small difference such as 380 V vs 400 V may be within component tolerances, but the manufacturer must confirm this for every motor, drive, heater, control transformer and single-phase load.

What changes on 60 Hz

An induction motor's speed is set by supply frequency and its number of poles. On 60 Hz a motor designed for 50 Hz turns about 20% faster (a four-pole motor's synchronous speed rises from 1,500 to 1,800 rpm). US Motors' note on the reverse case explains that voltage must change in proportion to frequency to keep volts-per-hertz constant, otherwise the motor must be derated, by factors of 0.70 to 0.85 depending on enclosure and pole count (US Motors). On a textile machine, an uncontrolled 20% speed rise on a fan, pump or directly driven spindle changes air flow, tension and process results, and can overload the motor. On a two-for-one twister, a change in spindle speed without matching delivery changes twist per metre.

Most modern machines run their main motors through frequency inverters, which set motor frequency independently of the grid, so main drives are usually less affected, but the inverter's input rating must accept your voltage and frequency, and any motors connected directly to the mains (fans, pumps, small auxiliaries) still change speed. Ask for a list of these direct-on-line motors and how each will be adapted, and include inverters in the spare parts list if they are built for a non-standard supply.

If the supplier cannot build for your supply, the alternatives are a step-up or step-down transformer (which corrects voltage only) or a frequency converter for the whole machine. Both add cost, space and losses; price them in.

Earthing, protection and documentation

IEC 60204-1, *Safety of machinery – Electrical equipment of machines – Part 1: General requirements*, covers machine electrical equipment from the point where the supply connects to it, including protective bonding, overcurrent and short-circuit protection, emergency stop, power drive systems and technical documentation (IEC). Ask which edition the machine follows, and request the electrical schematics, short-circuit rating and protective earth arrangements. Whether a supplier can produce these documents quickly is itself a useful signal about the factory. Tell the supplier your earthing system (for example TN-S, TN-C-S or IT).

EU and other conformity rules, at a high level

For the EU, machinery placed on the market from 20 January 2027 falls under Machinery Regulation (EU) 2023/1230, which replaces Directive 2006/42/EC and requires products to meet the essential health and safety requirements in its Annex III (EU-OSHA). Electromagnetic compatibility falls under Directive 2014/30/EU; the European Commission stresses that CE marking may be affixed only after the required conformity assessment, and that voluntary certificates are not recognised proof of compliance (European Commission). Other markets have their own rules; check them with your importer before signing.

Where power figures in listed equipment need checking

The B-type opening and squeezing series defines a 38 kW arrangement with a 6 m overall height, a useful sizing figure but not a consumption figure. The LH2000 water-jet loom catalogue has an unreadable motor-power entry that must be resolved before electrical planning. A hot-air stenter family publishes separate sheets for the oven air path and burners, and the JY-2025 stenter page describes a smaller oven volume and 150 mm insulation panels without a full operating-range table; in both cases, define the stenter and heat-setting process before comparing energy claims.

What to state in the enquiry

• Site supply: voltage, frequency, tolerance, number of phases and earthing system.
• Whether all motors, inverters, heaters and control circuits must be built for that supply.
• A request for installed power, broken down by main drive, heaters and auxiliaries.
• A request for measured kWh per kg or per hour at named settings, with the measurement method.
• Compressed air, suction and humidification needs, stated separately.
• Required documents: electrical schematics, conformity declaration for your market, standards applied.

The guide to preparing a weaving enquiry shows how to lay out the rest of the brief.

Sources

1. "Determining Electric Motor Load and Efficiency" (fact sheet), US Department of Energy, accessed 2026-11-04. View source
2. "GB/T 156-2017 Standard voltages" (English edition; issued by AQSIQ and SAC, implemented 2018-05-01), Codeofchina, accessed 2026-11-04. View source
3. "50 Hertz Operation of 60 Hertz Motors" (Product Facts), US Motors / Nidec Motor Corporation, accessed 2026-11-04. View source
4. "IEC 60204-1:2016 – Safety of machinery – Electrical equipment of machines – Part 1: General requirements", International Electrotechnical Commission (IEC webstore), accessed 2026-11-04. View source
5. "Regulation (EU) 2023/1230 – machinery", European Agency for Safety and Health at Work (EU-OSHA), accessed 2026-11-04. View source
6. "Electromagnetic compatibility (EMC) Directive", European Commission, Internal Market, Industry, Entrepreneurship and SMEs, accessed 2026-11-04. View source