{"id":164,"date":"2026-07-08T08:56:00","date_gmt":"2026-07-08T08:56:00","guid":{"rendered":"https:\/\/industrialelectricmotor.net\/?p=164"},"modified":"2026-07-08T08:56:00","modified_gmt":"2026-07-08T08:56:00","slug":"how-to-read-an-electric-motor-nameplate","status":"publish","type":"post","link":"https:\/\/industrialelectricmotor.net\/es\/how-to-read-an-electric-motor-nameplate\/","title":{"rendered":"How to Read an Electric Motor Nameplate"},"content":{"rendered":"
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Korea Ever-Power \u00b7 Nameplate Guide \u00b7 IEC 60034-1<\/span><\/p>\n

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How to Read an Electric Motor Nameplate:
\nComplete Guide to Every Rating<\/span><\/h1>\n

The motor nameplate is the single authoritative source for every electrical, mechanical, and environmental specification of the motor. It determines cable sizing, protection relay settings, starter selection, bearing replacement specification, and energy cost calculations. This guide explains what every field on an IEC motor nameplate means and how to use the data correctly in practice.<\/p>\n

Power and Voltage<\/span>
\nSpeed and Frequency<\/span>
\nEfficiency and cos\u03c6<\/span>
\nIP and Insulation<\/span>
\nFrame and Mounting<\/span><\/div>\n<\/div>\n<\/div>\n

<\/p>\n

\"Electric<\/p>\n
Korea Ever-Power Y2 series motor \u2014 the nameplate affixed to the terminal box contains all the data needed to select cables, starters, and protection relays and to calculate running costs. Learning to read a motor nameplate accurately is a fundamental skill for any electrical, mechanical, or maintenance engineer working with industrial drives.<\/div>\n<\/div>\n

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Contents<\/div>\n
1. Why the Nameplate Is the Primary Data Source<\/a>
\n2. Power, Voltage, and Current<\/a>
\n3. Speed, Frequency, and Slip<\/a>
\n4. Efficiency Class and Power Factor<\/a>
\n5. IP Rating, Insulation Class, and Duty Type<\/a>
\n6. Frame Size and Mounting Code<\/a>
\n7. Worked Example: Reading a Full Nameplate<\/a>
\n8. Frequently Asked Questions<\/a><\/div>\n<\/div>\n

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1. Why the Nameplate Is the Primary Data Source<\/h2>\n

IEC 60034-1 (Rotating Electrical Machines \u2014 Rating and Performance) specifies the data that must appear on every AC motor nameplate. The nameplate values are the rated conditions at which the motor meets all its performance guarantees simultaneously. Running the motor outside the nameplate operating range \u2014 higher current, lower voltage, excessive ambient temperature \u2014 does not necessarily cause immediate failure, but it reduces insulation life, bearing life, and long-term reliability in proportion to the degree and duration of the exceedance.<\/p>\n

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IEC 60034-1 Mandatory Nameplate Data<\/div>\n
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\u00b7 Manufacturer name and country<\/div>\n
\u00b7 Motor type \/ model designation<\/div>\n
\u00b7 Rated output power (kW)<\/div>\n
\u00b7 Rated voltage (V) and connection<\/div>\n
\u00b7 Rated frequency (Hz)<\/div>\n
\u00b7 Rated full-load current (A)<\/div>\n
\u00b7 Rated speed (rpm)<\/div>\n
\u00b7 Efficiency class (IE2\/IE3\/IE4)<\/div>\n
\u00b7 Power factor (cos \u03c6)<\/div>\n
\u00b7 Insulation class<\/div>\n
\u00b7 Enclosure protection (IP code)<\/div>\n
\u00b7 Duty type (S1\u2013S9)<\/div>\n
\u00b7 Ambient temperature range<\/div>\n
\u00b7 Altitude limit (if above 1,000 m)<\/div>\n
\u00b7 Frame size (IEC 72-1)<\/div>\n
\u00b7 Mounting code (IM designation)<\/div>\n
\u00b7 Serial number and year of manufacture<\/div>\n
\u00b7 Mass (kg)<\/div>\n<\/div>\n<\/div>\n<\/div>\n

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2. Power, Voltage, and Current<\/h2>\n
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Rated Output Power (kW)<\/div>\n

The shaft mechanical output power at rated conditions. This is what the motor delivers to the load \u2014 not the electrical power consumed. Electrical input power (kW consumed from supply) equals rated output divided by efficiency. A motor nameplate showing 15 kW at 92.5% efficiency consumes 15 \u00f7 0.925 = 16.2 kW from the supply at full rated load.<\/p>\n

P\u2011input = P\u2011nameplate \u00f7 \u03b7 \u2014 always greater than the nameplate value<\/div>\n<\/div>\n
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Rated Voltage (V) and Connection<\/div>\n

The supply voltage at which the motor is designed to operate, and whether it should be connected in star (Y) or delta (\u25b3) for that voltage. A nameplate showing \u201c380 V Y\u201d means connect in star on a 380 V supply. \u201c220\/380 V \u25b3\/Y\u201d means delta for 220 V or star for 380 V. Operating above or below rated voltage by more than \u00b15% degrades motor performance and shortens service life.<\/p>\n

The connection symbol (Y or \u25b3) on the nameplate must match the terminal link arrangement in the terminal box<\/div>\n<\/div>\n
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Rated Full-Load Current (A)<\/div>\n

The line current the motor draws from the supply when producing rated output power at rated voltage and frequency. This value is used to: set the overload protection relay (typically 100 to 105% of this value); size the supply cables (cable must carry this current continuously); select the contactor current rating; and calculate reactive power demand for power factor correction planning.<\/p>\n

Starting current = 5\u20138 \u00d7 rated current for 2\u201310 seconds on DOL start \u2014 cable and fuse must survive this transient<\/div>\n<\/div>\n<\/div>\n
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Three-phase motor input power formula: P\u2011input (kW) = \u221a3 \u00d7 V (kV) \u00d7 I (A) \u00d7 cos\u03c6 \u2014 where V is the line-to-line voltage and I is the rated line current from the nameplate. You can verify the nameplate current is consistent with the stated power and power factor using this formula.<\/p>\n<\/div>\n<\/div>\n

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3. Speed, Frequency, and Slip<\/h2>\n

The rated speed shown on the nameplate is the actual rotor speed at full load \u2014 always slightly below the synchronous speed determined by pole count and supply frequency. This difference is the slip.<\/p>\n

\n\n\n\n\n\n\n\n\n
Poles<\/th>\nSynchronous Speed (50 Hz)<\/th>\nTypical Nameplate Speed<\/th>\nSlip at Full Load<\/th>\nTypical Applications<\/th>\n<\/tr>\n<\/thead>\n
2<\/td>\n3,000 rpm<\/td>\n2,850\u20132,900 rpm<\/td>\n1.7\u20135%<\/td>\nCentrifugal fans, turboblowers, high-speed pumps<\/td>\n<\/tr>\n
4<\/td>\n1,500 rpm<\/td>\n1,420\u20131,460 rpm<\/td>\n2.7\u20135.3%<\/td>\nGeneral purpose: pumps, conveyors, compressors, machine tools<\/td>\n<\/tr>\n
6<\/td>\n1,000 rpm<\/td>\n940\u2013970 rpm<\/td>\n3\u20136%<\/td>\nAgitators, large fans, slow speed conveyors, kilns<\/td>\n<\/tr>\n
8<\/td>\n750 rpm<\/td>\n700\u2013730 rpm<\/td>\n4\u20136.7%<\/td>\nVery slow loads, large agitators, grain handling, direct drives<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n

The rated speed on the nameplate allows you to calculate the shaft torque at rated power: T (N\u00b7m) = 9,550 \u00d7 P (kW) \u00f7 n (rpm). For a 4 kW motor at 1,440 rpm, rated torque = 9,550 \u00d7 4 \u00f7 1,440 = 26.5 N\u00b7m. This torque value is needed to specify the coupling between the motor and driven machine.<\/p>\n<\/div>\n

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4. Efficiency Class and Power Factor<\/h2>\n
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Efficiency (\u03b7%) and IE Class<\/div>\n

The efficiency value on the nameplate is the ratio of shaft output power to electrical input power at rated load, measured at rated voltage and frequency. The IE class (IE2, IE3, IE4) indicates which international efficiency tier the motor achieves. These two items together tell you the energy cost of operating the motor: annual energy cost = (rated kW \u00f7 \u03b7) \u00d7 operating hours \u00d7 electricity rate (\u00a3\/kWh or $\/kWh).<\/p>\n

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Example calculation:<\/div>\n
7.5 kW IE3 motor, \u03b7 = 89.8%, 4,000 h\/yr, $0.13\/kWh
\nAnnual cost = (7.5 \u00f7 0.898) \u00d7 4,000 \u00d7 0.13 = $4,344\/yr<\/strong><\/div>\n<\/div>\n<\/div>\n
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Power Factor (cos \u03c6)<\/div>\n

The ratio of active power (kW) to apparent power (kVA). A motor with cos \u03c6 of 0.86 draws more apparent current than its active power consumption suggests: apparent current = active current \u00f7 cos \u03c6. This matters for cable sizing (cables carry apparent current, not just active power current) and for facilities that pay reactive power tariffs on industrial supply contracts. The nameplate power factor is measured at full rated load; at 50% load it typically falls to 0.65 to 0.75, and below 25% load can drop below 0.5.<\/p>\n

Apparent power: S (kVA) = P (kW) \u00f7 cos \u03c6 \u2014 use this for transformer and UPS sizing<\/div>\n<\/div>\n<\/div>\n<\/div>\n

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5. IP Rating, Insulation Class, and Duty Type<\/h2>\n
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IP Code (e.g. IP55)<\/div>\n

The two digits of the IP code (IEC 60529) indicate solid particle and water ingress protection. The first digit (0\u20136) indicates dust protection: 5 = dust-protected, 6 = dust-tight. The second digit (0\u20139K) indicates water protection: 4 = splash, 5 = water jets, 6 = powerful jets, 7 = temporary immersion, 8 = continuous immersion, 9K = high-pressure hot water jets. The IP code determines where the motor can be installed: IP44 for clean indoor use, IP55 for general industrial, IP65 for washdown areas, IP69K for food and pharmaceutical high-pressure washdown.<\/p>\n

The IP rating applies to the complete assembled motor including the terminal box<\/div>\n<\/div>\n
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Insulation Class (e.g. Class F)<\/div>\n

The insulation class defines the maximum permissible winding temperature. Class B = 130\u00b0C, Class F = 155\u00b0C, Class H = 180\u00b0C. Korea Ever-Power Y2 series motors use Class F insulation with temperature rise limited to 80 K (Class B rise), giving a thermal reserve of 25 K above the ambient-plus-rise sum that extends insulation life significantly. The insulation class constrains the maximum ambient temperature at which the motor can operate at full load \u2014 at ambient above 40\u00b0C, a motor with Class F insulation and Class B rise must be derated.<\/p>\n

Max winding temp = ambient + temp rise class limit \u2014 must stay below insulation class limit<\/div>\n<\/div>\n
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Duty Type (e.g. S1)<\/div>\n

IEC 60034-1 defines nine duty types (S1 to S9) describing how the motor\u2019s load varies over time. S1 means the motor runs continuously at constant load long enough to reach thermal equilibrium \u2014 this is the most common and the most demanding duty from a thermal perspective. S3 (intermittent periodic duty with a stated cyclic duty factor) allows a motor to carry a higher nameplate power because it has rest periods for cooling. A motor rated for S3 duty at 40% CDF must not be used in S1 continuous duty without derating.<\/p>\n

S1 = continuous duty \u2014 the default for pumps, fans, compressors, and most industrial drives<\/div>\n<\/div>\n<\/div>\n<\/div>\n

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6. Frame Size and Mounting Code<\/h2>\n
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The IEC frame size designation (e.g. 132S, 160M, 200L) encodes the shaft height and the stator stack length. The number is the shaft height in mm measured from the motor base to the shaft centre. The letter suffix (S = short, M = medium, L = long) indicates the stack length within that shaft height, determining the active copper and iron volume and therefore the power output at each shaft height.<\/p>\n

The IEC mounting code (IM designation) on the nameplate specifies how the motor is installed: foot, flange, vertical, or combined. IM B3 = foot horizontal, IM B5 = flange horizontal, IM B35 = foot plus flange. For three-phase motors<\/a> in IEC frames, the shaft height and foot hole spacing are standardised by IEC 72-1, ensuring mechanical interchangeability between motors of the same frame designation from different manufacturers.<\/p>\n<\/div>\n

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IEC Frame Size Reference<\/div>\n\n\n\n\n\n\n\n\n\n\n\n\n
Frame<\/th>\nShaft Height<\/th>\nTypical kW Range<\/th>\n<\/tr>\n<\/thead>\n
71<\/td>\n71 mm<\/td>\n0.18\u20130.55<\/td>\n<\/tr>\n
80<\/td>\n80 mm<\/td>\n0.37\u20130.75<\/td>\n<\/tr>\n
90<\/td>\n90 mm<\/td>\n0.75\u20132.2<\/td>\n<\/tr>\n
100<\/td>\n100 mm<\/td>\n2.2\u20133.0<\/td>\n<\/tr>\n
112<\/td>\n112 mm<\/td>\n3.0\u20135.5<\/td>\n<\/tr>\n
132<\/td>\n132 mm<\/td>\n5.5\u201311<\/td>\n<\/tr>\n
160<\/td>\n160 mm<\/td>\n11\u201318.5<\/td>\n<\/tr>\n
180\u2013315<\/td>\n180\u2013315 mm<\/td>\n22\u2013200+<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n

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7. Worked Example: Reading a Full Nameplate<\/h2>\n

The following example shows how to extract practical engineering values from a typical Korea Ever-Power Y2 series nameplate:<\/p>\n

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Korea Ever-Power \u00b7 Three-Phase Induction Motor \u00b7 Y2-160M-4<\/div>\n
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Rated Power<\/div>\n
11 kW<\/div>\n<\/div>\n
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Voltage \/ Connection<\/div>\n
380 V Y<\/div>\n<\/div>\n
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Rated Current<\/div>\n
22.6 A<\/div>\n<\/div>\n
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Frequency<\/div>\n
50 Hz<\/div>\n<\/div>\n
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Rated Speed<\/div>\n
1,460 rpm<\/div>\n<\/div>\n
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Efficiency \/ IE Class<\/div>\n
91.0% IE3<\/div>\n<\/div>\n
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Power Factor<\/div>\n
cos \u03c6 0.87<\/div>\n<\/div>\n
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IP \/ Insulation<\/div>\n
IP54 \/ F<\/div>\n<\/div>\n
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Duty \/ Ambient<\/div>\n
S1 \/ 40\u00b0C<\/div>\n<\/div>\n
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Frame \/ Mounting<\/div>\n
160M \/ B3<\/div>\n<\/div>\n
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Mass<\/div>\n
118 kg<\/div>\n<\/div>\n<\/div>\n<\/div>\n

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What This Nameplate Tells You<\/h3>\n
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Electrical input power<\/div>\n
11 \u00f7 0.910 = 12.1 kW consumed<\/strong> from supply at full load<\/div>\n<\/div>\n
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Apparent power (kVA)<\/div>\n
12.1 \u00f7 0.87 = 13.9 kVA<\/strong> \u2014 use for transformer sizing<\/div>\n<\/div>\n
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Overload relay setting<\/div>\n
Set at 22.6 A<\/strong> (nameplate FLC) \u2014 never set higher<\/div>\n<\/div>\n
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Shaft torque at rated load<\/div>\n
9,550 \u00d7 11 \u00f7 1,460 = 72 N\u00b7m<\/strong> \u2014 for coupling selection<\/div>\n<\/div>\n
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Annual energy cost<\/div>\n
12.1 kW \u00d7 4,000 h \u00d7 $0.12 = $5,808\/yr<\/strong><\/div>\n<\/div>\n
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Installation environment<\/div>\n
IP54 = dusty industrial indoor. Not suitable for washdown or outdoor without additional protection.<\/div>\n<\/div>\n
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Mounting arrangement<\/div>\n
IM B3 = foot-mounted, shaft horizontal. 160M frame gives shaft height 160 mm, standard IEC72-1 foot hole spacing.<\/div>\n<\/div>\n
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Slip at rated load<\/div>\n
(1,500 \u2212 1,460) \u00f7 1,500 = 2.7%<\/strong> \u2014 within normal range for 4-pole motor<\/div>\n<\/div>\n<\/div>\n<\/div>\n

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\"Korea<\/p>\n

CNC Precision Machining<\/div>\n<\/div>\n
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\"Korea<\/p>\n

Performance Testing<\/div>\n<\/div>\n
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\"Korea<\/p>\n

Export Packaging<\/div>\n<\/div>\n
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\"Korea<\/p>\n

Worldwide Delivery<\/div>\n<\/div>\n<\/div>\n

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8. Frequently Asked Questions<\/h2>\n
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Why does my motor draw more current than the nameplate rating even when the load seems normal?<\/div>\n<\/div>\n
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Several factors can cause a motor to draw above-nameplate current without being mechanically overloaded. Low supply voltage is the most common \u2014 when voltage drops below rated, the motor draws higher current to maintain the same output power. A 5% voltage reduction causes approximately a 10% current increase. Supply voltage imbalance between phases causes the motor to draw higher current in one or two phases. Elevated ambient temperature raises winding resistance and can increase current slightly. Measuring all three phase voltages at the motor terminals (not at the panel) while the motor runs at full load will identify voltage-related overcurrent.<\/p>\n<\/div>\n<\/div>\n

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The nameplate says Class F insulation but Class B rise \u2014 what does that mean in practice?<\/div>\n<\/div>\n
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Class F insulation can withstand a maximum winding temperature of 155\u00b0C. Class B temperature rise is limited to 80 K above ambient. At standard 40\u00b0C ambient, the winding therefore reaches 40 + 80 = 120\u00b0C at rated full load \u2014 which is 35 K below the Class F limit of 155\u00b0C. This 35 K thermal reserve dramatically extends insulation service life: insulation life roughly doubles for every 10 K reduction in operating temperature (the Montsinger Rule). A motor running at 120\u00b0C (Class F insulation, Class B rise) will have approximately 8 times the insulation life of the same insulation running at 150\u00b0C. This is why Korea Ever-Power specifies Class F insulation with Class B rise as standard for all Y2 series motors \u2014 it provides meaningful long-term service life advantage without any additional cost.<\/p>\n<\/div>\n<\/div>\n

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Can I use a 50 Hz motor on a 60 Hz supply?<\/div>\n<\/div>\n
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Running a 50 Hz motor on 60 Hz supply increases the synchronous speed by 20% (a 4-pole motor runs at 1,800 rpm instead of 1,500 rpm) and increases the iron core magnetising frequency, which raises iron losses and core temperature. The motor must be derated to prevent overheating \u2014 typically to 83% of nameplate power at 60 Hz on a 50 Hz motor. The fan also runs faster, providing more cooling, which partially offsets the increased losses. Korea Ever-Power can supply motors rated for dual-frequency operation (50\/60 Hz dual-rated) on request; these have nameplate data for both frequencies and can be used without derating at either supply frequency.<\/p>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n

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Korea Ever-Power \u00b7 Y2 Series Three-Phase Motors<\/div>\n

Need a Y2 Series Motor or Nameplate Data Sheet?<\/h2>\n

Korea Ever-Power provides full dimensional drawings, nameplate data, and performance curves for all Y2 series motors from 0.18 to 200 kW. Request technical data for your frame size from our engineering team.<\/p>\n

Browse Motor Range<\/a><\/p>\n<\/div>\n<\/div>\n

Edited by Cxm<\/p>\n<\/div>","protected":false},"excerpt":{"rendered":"

Korea Ever-Power \u00b7 Nameplate Guide \u00b7 IEC 60034-1 How to Read an Electric Motor Nameplate: Complete Guide to Every Rating The motor nameplate is the single authoritative source for every electrical, mechanical, and environmental specification of the motor. It determines cable sizing, protection relay settings, starter selection, bearing replacement specification, and energy cost calculations. This […]<\/p>","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"_et_pb_use_builder":"","_et_pb_old_content":"","_et_gb_content_width":"","footnotes":""},"categories":[28],"tags":[],"class_list":["post-164","post","type-post","status-publish","format-standard","hentry","category-industrial-electric-motor"],"_links":{"self":[{"href":"https:\/\/industrialelectricmotor.net\/es\/wp-json\/wp\/v2\/posts\/164","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/industrialelectricmotor.net\/es\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/industrialelectricmotor.net\/es\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/industrialelectricmotor.net\/es\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/industrialelectricmotor.net\/es\/wp-json\/wp\/v2\/comments?post=164"}],"version-history":[{"count":1,"href":"https:\/\/industrialelectricmotor.net\/es\/wp-json\/wp\/v2\/posts\/164\/revisions"}],"predecessor-version":[{"id":171,"href":"https:\/\/industrialelectricmotor.net\/es\/wp-json\/wp\/v2\/posts\/164\/revisions\/171"}],"wp:attachment":[{"href":"https:\/\/industrialelectricmotor.net\/es\/wp-json\/wp\/v2\/media?parent=164"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/industrialelectricmotor.net\/es\/wp-json\/wp\/v2\/categories?post=164"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/industrialelectricmotor.net\/es\/wp-json\/wp\/v2\/tags?post=164"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}