{"id":155,"date":"2026-07-08T08:50:06","date_gmt":"2026-07-08T08:50:06","guid":{"rendered":"https:\/\/industrialelectricmotor.net\/?p=155"},"modified":"2026-07-08T08:50:06","modified_gmt":"2026-07-08T08:50:06","slug":"how-to-install-a-three-phase-electric-motor","status":"publish","type":"post","link":"https:\/\/industrialelectricmotor.net\/ja\/how-to-install-a-three-phase-electric-motor\/","title":{"rendered":"How to Install a Three-Phase Electric Motor"},"content":{"rendered":"
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Korea Ever-Power \u00b7 Installation Guide \u00b7 IEC 60034<\/span><\/p>\n

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How to Install a Three-Phase Electric Motor:
\nStep-by-Step Guide<\/span><\/h1>\n

A correct motor installation is the foundation of long service life and low maintenance cost. Most premature motor failures trace back to errors made at installation \u2014 misalignment, incorrect coupling, wrong terminal connection, or inadequate foundation preparation. This guide covers every step from unpacking to first run for three-phase induction motors in IEC frame sizes 71 through 315.<\/p>\n

Foundation and Mounting<\/span>
\nShaft Alignment<\/span>
\nTerminal Wiring<\/span>
\nPre-Start Checks<\/span>
\nFirst Run Commissioning<\/span><\/div>\n<\/div>\n<\/div>\n

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01<\/div>\n
Unpack and Inspect<\/div>\n<\/div>\n
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02<\/div>\n
Prepare Foundation<\/div>\n<\/div>\n
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03<\/div>\n
Mount the Motor<\/div>\n<\/div>\n
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04<\/div>\n
Align the Shaft<\/div>\n<\/div>\n
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05<\/div>\n
Wire Terminals<\/div>\n<\/div>\n
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06<\/div>\n
Test and Commission<\/div>\n<\/div>\n<\/div>\n

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\"Three-phase<\/p>\n
IEC mounting configurations \u2014 IMB3 (foot-mounted), IMB5 (flange-mounted), and IMB35 (foot and flange combined) are the three most common three-phase motor mounting arrangements in industrial installations. The choice affects both the foundation preparation method and the alignment procedure.<\/div>\n<\/div>\n

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Contents<\/div>\n
Step 1. Unpacking and Pre-Installation Inspection<\/a>
\nStep 2. Foundation and Baseplate Preparation<\/a>
\nStep 3. Mounting the Motor<\/a>
\nStep 4. Shaft Alignment<\/a>
\nStep 5. Electrical Connection and Grounding<\/a>
\nStep 6. Pre-Start Checks and First Run<\/a>
\nIEC Mounting Method Reference<\/a>
\nFrequently Asked Questions<\/a><\/div>\n<\/div>\n

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Step 1. Unpacking and Pre-Installation Inspection<\/h2>\n

Before any mechanical work begins, inspect the motor carefully. Damage during transport is common and must be identified before installation, not after the motor has been wired into a control panel and connected to a driven machine.<\/p>\n

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Visual external check<\/div>\n

Examine the frame, end shields, fan cover, terminal box, and shaft extension for cracks, dents, or impact damage. Check that the shaft rotates freely by hand with smooth resistance \u2014 any roughness, grinding, or hard spots indicate bearing damage from shock loading in transit. Check the nameplate is intact and legible.<\/p>\n<\/div>\n

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Insulation resistance test<\/div>\n

Before connecting any supply cable, test the stator winding insulation resistance with a 500 V DC megohmmeter (for motors up to 1 kV rated voltage). Minimum acceptable reading is 1 M\u03a9 at 20\u00b0C ambient. A motor stored in a humid environment may show lower values; if reading is below 1 M\u03a9, dry the motor in an oven at 80\u00b0C for 6 to 12 hours before proceeding.<\/p>\n<\/div>\n

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Nameplate verification<\/div>\n

Confirm the motor nameplate data matches the application requirements: power rating (kW), voltage (V), frequency (Hz), connection (star or delta), speed (rpm), frame size, IP rating, insulation class, and duty type. If any parameter does not match the specification, do not install the motor until the discrepancy is resolved with the supplier.<\/p>\n<\/div>\n

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Shaft and keyway check<\/div>\n

Check the shaft extension diameter and length against the coupling or sprocket bore dimensions. Verify the keyway dimensions (width and depth) match the key that will transmit torque to the driven component. Any burrs or raised edges on the shaft from transit contact must be removed with a fine file before fitting any power transmission element.<\/p>\n<\/div>\n<\/div>\n<\/div>\n

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Step 2. Foundation and Baseplate Preparation<\/h2>\n

The motor foundation must be rigid enough to prevent vibration amplification during running, flat enough to avoid frame distortion when the hold-down bolts are tightened, and level to within the tolerance required for shaft alignment. A poorly prepared foundation is the most common cause of persistent vibration, premature bearing failure, and recurring alignment loss in industrial motor installations.<\/p>\n

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Foundation Requirements<\/div>\n\n\n\n\n\n\n\n
Frame flatness tolerance<\/td>\n\u2264 0.1 mm over mounting footprint<\/td>\n<\/tr>\n
Levelness<\/td>\n\u2264 0.05 mm\/m in all directions<\/td>\n<\/tr>\n
Foundation stiffness<\/td>\nMin. 3\u00d7 motor + driven machine mass<\/td>\n<\/tr>\n
Anchor bolt diameter<\/td>\nPer IEC 72-1 frame foot hole size<\/td>\n<\/tr>\n
Grout (grouted bases)<\/td>\nNon-shrink epoxy grout<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n<\/div>\n
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For motors mounted on structural steel frames or machinery sub-frames (common for pump and fan sets), the baseplate must be checked for flatness with a precision straight-edge and feeler gauges before bolting the motor down. Any gap greater than 0.05 mm under the motor feet must be corrected with stainless steel shim packs, not by over-tightening the hold-down bolts, which will introduce frame distortion and stator bore ovality.<\/p>\n

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Soft foot warning: tightening hold-down bolts on an uneven base distorts the motor frame, slightly deforming the stator bore and reducing the air gap uniformity between stator and rotor. This causes increased vibration, noise, and in severe cases accelerates winding failure through stator-rotor contact. Always correct soft foot before final bolt torque.<\/p>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n

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Step 3. Mounting the Motor<\/h2>\n

How the motor is mounted depends on whether it uses foot mounting (IMB3), flange mounting (IMB5), or the combined foot-and-flange arrangement (IMB35). The drive side (DE) bearing carries radial loads from belt, chain, or gear drives; the non-drive end (NDE) bearing is lightly loaded and carries mainly the rotor weight.<\/p>\n

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Mounting Code<\/th>\nDescription<\/th>\nTypical Application<\/th>\nKey Installation Note<\/th>\n<\/tr>\n<\/thead>\n
IMB3<\/td>\nFoot-mounted, shaft horizontal<\/td>\nMost pumps, fans, compressors, conveyors<\/td>\nFour-point foot contact; check all four feet for soft foot before final torque<\/td>\n<\/tr>\n
IMB5<\/td>\nFlange-mounted, shaft horizontal<\/td>\nClose-coupled pumps, gearboxes, direct machine mounting<\/td>\nFlange register (spigot) must be clean and undamaged; check concentricity with dial gauge<\/td>\n<\/tr>\n
IMB35<\/td>\nFoot and flange, shaft horizontal<\/td>\nLarge geared pump sets, heavy machine tool drives<\/td>\nFlange carries alignment; feet provide stability only. Fit flange first, then shim feet to contact<\/td>\n<\/tr>\n
IMV1<\/td>\nFoot-mounted, shaft vertical downward<\/td>\nVertical pump sets, mixer agitator drives<\/td>\nConfirm motor specified for vertical operation; NDE bearing must carry rotor weight axially<\/td>\n<\/tr>\n
IMV3<\/td>\nFlange-mounted, shaft vertical upward<\/td>\nCeiling-mounted fans, overhead conveyors<\/td>\nFan cover must face down for ventilation; confirm correct fan orientation before installation<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n

For belt-driven applications (the most common indirect drive arrangement for three-phase motors), the belt tension must be set correctly after alignment. Insufficient belt tension causes slip and belt overheating; excessive tension imposes radial overhang load on the drive-end bearing beyond the motor\u2019s rated overhang capacity, dramatically shortening bearing service life. Consult the Korea Ever-Power bearing load capacity table for each frame size, available from the technical support team<\/a>.<\/p>\n<\/div>\n

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Step 4. Shaft Alignment<\/h2>\n

Shaft misalignment between the motor and driven machine is the leading cause of premature bearing failure, coupling wear, and excessive vibration in direct-coupled motor-drive trains. Even a well-commissioned motor will fail within a fraction of its expected bearing life if the shaft alignment is outside tolerance. Two types of misalignment must both be corrected:<\/p>\n

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Parallel (Offset) Misalignment<\/div>\n

The shaft centrelines are parallel but offset in the radial direction. Measured as the gap difference between coupling halves at top-bottom or left-right positions using a dial indicator rotated around the coupling. Maximum permissible parallel offset for flexible couplings: typically 0.05 to 0.10 mm for motor frame sizes up to 200, 0.10 to 0.15 mm for frame 250 and above.<\/p>\n

Correction: raise or lower motor with shim packs; shift motor laterally on slotted mounting holes<\/div>\n<\/div>\n
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Angular Misalignment<\/div>\n

The shaft centrelines intersect at an angle rather than being collinear. Measured as the face gap difference between the two coupling halves at diametrically opposite positions (top vs bottom, or left vs right). Maximum permissible angular misalignment: typically 0.05 mm per 100 mm coupling face diameter, equivalent to approximately 0.03\u00b0.<\/p>\n

Correction: adjust shim pack thickness under individual motor feet to tilt motor shaft angle<\/div>\n<\/div>\n<\/div>\n
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Alignment Method Comparison<\/div>\n
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Straight-Edge and Feeler Gauge<\/div>\n

Lowest cost; suitable for preliminary rough alignment and belt-driven applications. Accuracy: \u00b10.1 mm typical. Not adequate for high-speed or high-precision direct couplings.<\/p>\n<\/div>\n

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Dial Indicator Method<\/div>\n

Standard industrial method. One or two dial gauges mounted on one coupling half, reading against the other. Accuracy: \u00b10.02 mm with care. Adequate for most motor installations up to 3,000 rpm.<\/p>\n<\/div>\n

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Laser Alignment System<\/div>\n

Highest accuracy and fastest measurement. Laser emitter and receiver clamp to each shaft; digital readout gives real-time offset and angle values in both planes simultaneously. Accuracy: \u00b10.005 mm. Required for motors above 1,000 kW or above 3,000 rpm.<\/p>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n

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Step 5. Electrical Connection and Grounding<\/h2>\n

The terminal box of a three-phase induction motor contains six terminals: U1, V1, W1 (supply end of each phase winding) and U2, V2, W2 (other end of each phase winding). The connection arrangement determines whether the motor runs in star (Y) or delta (\u25b3) configuration, which determines the voltage the individual windings see and therefore the motor\u2019s operating voltage.<\/p>\n

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Star Connection (Y) \u2014 380 V Supply<\/div>\n

Connect U2, V2, W2 together at the star point using the shorting links provided. Connect the three-phase supply to U1, V1, W1. In star connection, each winding sees the phase voltage (380 V \u00f7 \u221a3 = 220 V). Star connection is used when the motor is rated 380 V\/220 V and the supply is 380 V three-phase.<\/p>\n

Link positions: U2-V2-W2 shorted. Supply to U1, V1, W1.<\/div>\n<\/div>\n
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Delta Connection (\u25b3) \u2014 220 V Supply<\/div>\n

Connect U1-W2, V1-U2, W1-V2 using the shorting links in a triangular (delta) arrangement. Connect the three-phase supply to the three link junction points. In delta connection, each winding sees the full line voltage (220 V). Delta is used when the supply is 220 V three-phase or when the motor is rated 660 V\/380 V on a 380 V supply.<\/p>\n

Link positions: U1-W2, V1-U2, W1-V2. Supply to the three junction points.<\/div>\n<\/div>\n<\/div>\n
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Phase rotation check: after wiring, but before connecting the driven load, run the motor briefly and check the shaft rotation direction. If it runs backward (wrong direction), swap any two of the three supply phases at the terminal box. Never correct motor rotation direction by mechanical means on the driven machine side.<\/p>\n<\/div>\n

The motor frame must be connected to the protective earth (PE) conductor of the supply cable at the earth terminal in the terminal box. The PE conductor cross-section must be at minimum equal to the supply phase conductor cross-section for conductors up to 16 mm\u00b2. Failure to earth the motor frame creates a dangerous shock hazard if an internal winding fault connects phase voltage to the frame.<\/p>\n<\/div>\n

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Step 6. Pre-Start Checks and First Run<\/h2>\n
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CHECK<\/div>\n
Insulation re-test<\/div>\n<\/div>\n

Repeat the megohmmeter test at 500 V DC between each phase and earth before energising. Reading must be above 1 M\u03a9. If any reading has fallen since the pre-installation test, investigate for moisture or wiring fault before proceeding.<\/p>\n<\/div>\n

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CHECK<\/div>\n
Protection relay settings<\/div>\n<\/div>\n

Set the thermal overload relay or motor protection relay to the motor nameplate full-load current. Do not set it higher \u201cto avoid nuisance trips\u201d \u2014 the overload relay is the last line of defence against overheating if the motor is overloaded or loses a phase.<\/p>\n<\/div>\n

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CHECK<\/div>\n
No-load first start<\/div>\n<\/div>\n

If possible, decouple the motor from the driven machine for the first run. This allows checking rotation direction, listening for bearing noise, and measuring no-load current (should be 30 to 60 percent of nameplate current) without risk to the driven equipment. Re-couple only after confirming correct direction and smooth running.<\/p>\n<\/div>\n

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CHECK<\/div>\n
Running current and temperature<\/div>\n<\/div>\n

After coupling and loading, measure all three phase currents with a clamp meter. They should be within 5 percent of each other and below the nameplate full-load current at the operating load. After 30 minutes of running at full load, check the motor frame temperature \u2014 it should be warm but not too hot to touch (Class F motors: frame temperature up to 70\u00b0C above ambient is normal).<\/p>\n<\/div>\n

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CHECK<\/div>\n
Vibration level<\/div>\n<\/div>\n

Measure vibration velocity at the bearing housings. IEC 60034-14 sets maximum vibration velocity at 2.8 mm\/s RMS for standard-grade motors in frame 56 to 400. Levels above 4.5 mm\/s indicate a problem \u2014 most commonly misalignment, unbalanced coupling, or resonance with the foundation structure.<\/p>\n<\/div>\n

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RECORD<\/div>\n
Commissioning record<\/div>\n<\/div>\n

Document the installation date, measured values (insulation resistance, current balance, vibration), alignment readings, coupling type and setting, overload relay setting, and initial bearing temperature. This baseline data is essential for condition monitoring comparison at future maintenance intervals.<\/p>\n<\/div>\n<\/div>\n<\/div>\n

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IEC Mounting Method Reference<\/h2>\n

\"Korea<\/p>\n

The full range of Korea Ever-Power Y2 series three-phase motors is available in all standard IEC mounting configurations. Terminal box position can be rotated to four positions to suit cable entry direction without changing the mounting arrangement. For detailed dimensional drawings and mounting bolt torque specifications for each frame size, consult the product pages<\/a> or request dimensional data from the Korea Ever-Power engineering team.<\/p>\n<\/div>\n

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\"Korea<\/p>\n

Pre-shipment testing<\/div>\n<\/div>\n
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\"Korea<\/p>\n

CNC frame machining<\/div>\n<\/div>\n
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\"Korea<\/p>\n

Ready-stock warehouse<\/div>\n<\/div>\n
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\"Korea<\/p>\n

Export packaging<\/div>\n<\/div>\n<\/div>\n

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Frequently Asked Questions<\/h2>\n
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How much coupling misalignment is acceptable for a direct-coupled motor?<\/div>\n<\/div>\n
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The acceptable misalignment depends on the coupling type and the rotational speed. For standard flexible jaw couplings at speeds up to 1,500 rpm (4-pole motor), manufacturers typically specify maximum parallel offset of 0.10 mm and maximum angular misalignment of 0.5\u00b0. At higher speeds (2-pole motors at 2,900 rpm), the limits tighten to 0.05 mm parallel and 0.15\u00b0 angular. Disc and membrane couplings are less tolerant of parallel offset and more tolerant of angular error. Always refer to the coupling manufacturer\u2019s alignment specification, not just the motor standard.<\/p>\n<\/div>\n<\/div>\n

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Can I connect a 380 V motor in delta on a 380 V supply to get more power?<\/div>\n<\/div>\n
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No. A motor rated 380 V must be connected in star on a 380 V supply. Connecting it in delta on 380 V would apply 380 V across each individual winding instead of 220 V (380 V \/ \u221a3). This would cause the winding current to increase by the square of the voltage ratio (approximately 3 times rated current) almost immediately, overheating and destroying the winding insulation within seconds. Dual-voltage motors (such as 220 V\/380 V) can be connected in delta on 220 V or star on 380 V, because in both cases the individual winding sees 220 V.<\/p>\n<\/div>\n<\/div>\n

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What causes motor vibration after installation and how is it diagnosed?<\/div>\n<\/div>\n
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The most common causes of excessive vibration in a newly installed motor drive are, in order of frequency: (1) shaft misalignment \u2014 parallel or angular, or both; (2) soft foot \u2014 one or more motor feet not properly contacting the baseplate; (3) unbalanced coupling or pulley \u2014 coupling elements not balanced as an assembly after fitting; (4) belt tension errors \u2014 over or under-tensioned belt drive creating variable radial load; (5) foundation resonance \u2014 the natural frequency of the baseplate or structure coincides with the motor running frequency. Frequency spectrum analysis of the vibration signal quickly identifies which of these is dominant, as each produces a characteristic frequency signature.<\/p>\n<\/div>\n<\/div>\n

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Do Korea Ever-Power motors require lubrication before installation?<\/div>\n<\/div>\n
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Korea Ever-Power Y2 series motors in frame sizes up to 160L use sealed-for-life bearings pre-packed with grease at the factory. No regreasing is required or possible for these sizes \u2014 the bearing should simply be replaced according to the service life schedule. Frame sizes 180M and above are fitted with re-greasable bearings with grease nipples on both drive-end and non-drive-end bearing housings. These motors are shipped with the bearings filled with grease and require no additional lubrication before commissioning, but do require periodic regreasing during service. The regreasing interval is stamped on the nameplate or stated in the installation manual for each frame size.<\/p>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n

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Korea Ever-Power \u00b7 Installation Support<\/div>\n

Need Technical Assistance with Motor Installation?<\/h2>\n

Korea Ever-Power provides dimensional drawings, mounting torque specifications, and installation guidance for all Y2, YB2, Y2EJ, YVF2, and BXG series motors. Technical enquiries welcome.<\/p>\n

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

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

Korea Ever-Power \u00b7 Installation Guide \u00b7 IEC 60034 How to Install a Three-Phase Electric Motor: Step-by-Step Guide A correct motor installation is the foundation of long service life and low maintenance cost. Most premature motor failures trace back to errors made at installation \u2014 misalignment, incorrect coupling, wrong terminal connection, or inadequate foundation preparation. This guide covers every step from unpacking to first run for three-phase induction motors in IEC frame sizes 71 through 315. Foundation and Mounting Shaft Alignment Terminal Wiring Pre-Start Checks First Run Commissioning 01 Unpack and Inspect 02 Prepare Foundation 03 Mount the Motor 04 Align the Shaft 05 Wire Terminals 06 Test and Commission IEC […]<\/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-155","post","type-post","status-publish","format-standard","hentry","category-industrial-electric-motor"],"_links":{"self":[{"href":"https:\/\/industrialelectricmotor.net\/ja\/wp-json\/wp\/v2\/posts\/155","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/industrialelectricmotor.net\/ja\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/industrialelectricmotor.net\/ja\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/industrialelectricmotor.net\/ja\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/industrialelectricmotor.net\/ja\/wp-json\/wp\/v2\/comments?post=155"}],"version-history":[{"count":1,"href":"https:\/\/industrialelectricmotor.net\/ja\/wp-json\/wp\/v2\/posts\/155\/revisions"}],"predecessor-version":[{"id":158,"href":"https:\/\/industrialelectricmotor.net\/ja\/wp-json\/wp\/v2\/posts\/155\/revisions\/158"}],"wp:attachment":[{"href":"https:\/\/industrialelectricmotor.net\/ja\/wp-json\/wp\/v2\/media?parent=155"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/industrialelectricmotor.net\/ja\/wp-json\/wp\/v2\/categories?post=155"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/industrialelectricmotor.net\/ja\/wp-json\/wp\/v2\/tags?post=155"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}