Grundfos MG Electric Motors: Installation and Operating Instructions
This document provides comprehensive instructions for the installation, operation, and maintenance of Grundfos MG series electric motors. It is essential to read and understand this guide before installing or operating the motor. Compliance with local regulations and accepted codes of good practice is mandatory.
1. General Information
This section outlines important hazard statements, notes, and safety guidelines applicable to Grundfos motors.
1.1 Hazard Statements
Symbols and statements indicate potential hazards:
- DANGER: Indicates a hazardous situation which, if not avoided, will result in death or serious personal injury.
- WARNING: Indicates a hazardous situation which, if not avoided, could result in death or serious personal injury.
- CAUTION: Indicates a hazardous situation which, if not avoided, could result in minor or moderate personal injury.
Hazard statements are structured with a SIGNAL WORD, Description of the hazard, Consequence of ignoring the warning, and Action to avoid the hazard.
1.2 Notes
Symbols and notes provide additional information:
- ℹ️: Observe these instructions for explosion-proof products.
- ?: A blue or grey circle with a white graphical symbol indicates that an action must be taken.
- ?: A red or grey circle with a diagonal bar indicates that an action must not be taken or must be stopped.
- ❗: If these instructions are not observed, it may result in malfunction or damage to the equipment.
- Tips and advice that make the work easier.
1.3 Safety
Observe all safety instructions to ensure correct installation, operation, and maintenance. Failure to do so may invalidate the warranty. Ensure necessary safety equipment is available.
2. Product Introduction
2.1 Product Description
These instructions apply to Grundfos MG motors. A table details available models, phase configurations, power ranges, and corresponding IEC frame sizes.
| Model | Phase | Power range [kW] | IEC frame size | ||
|---|---|---|---|---|---|
| 1 | 3 | 2-pole | 4-pole | ||
| B | • | 0.25 - 2.2 | 0.18 - 1.1 | 71 - 90 | 71 - 90 |
| C | • | 0.25 | - | 71 | 71 |
| D | • | 0.37 - 11 | 0.25 - 5.5 | 71 - 132 | 71 - 132 |
| F | • | 1.1 - 11 | 1.1 - 4.0 | 90 - 160 | 90 - 112 |
| H | • | 0.75 - 22 | 0.75 - 15 | 80 - 180 | 90 - 160 |
2.1.1 Application
MG motors are designed for use within the framework of IEC 60034.
2.2 Identification
2.2.1 Nameplate
Motors are equipped with two nameplates: one for electrical data (50/60 Hz) and one for mechanical data (frequency-independent). Both are located on the side of the motor.
2.2.2 Type Key
The type designation on the nameplate indicates motor specifications. For three-phase motors, both 50 and 60 Hz data are shown. For single-phase motors, only 50 or 60 Hz data are shown. Previous MG motor versions may only show 60 Hz data.
Example Type Designation: MG 132 S B 2-38 FF 265-H 3
The type key is explained as follows:
| Code | Explanation |
|---|---|
| MG | Motor Grundfos |
| 132 | Frame size (centre-line height of shaft, foot-mounted motor [mm]) |
| S | Size, foot: [ ] = frame sizes 71, 80; S = small; M = medium; L = large |
| B | Length of stator core: A, B, C, D |
| 2 | Number of poles: 2, 4 |
| -38 | Diameter of shaft end [mm] |
| FF | Flange version: [ ] = foot-mounted motor, type IM B 3; FF = free-hole flange; FT = tapped-hole flange |
| 265 | Pitch circle diameter [mm] |
| -H | Model: A (discontinued), B, C, D, F, H |
| 3 | Efficiency class: [ ] = NA; 1 = IE2 motor; 2 = IE1 motor; 3 = IE3 motor |
3. Receiving the Product
3.1 Inspecting the Product
Upon receipt, immediately check the motor for external damage. Contact the carrier if damage is found. Verify that all nameplate data match specifications, including voltage, and check the winding connection against the wiring diagram in the terminal box cover.
3.1.1 Unpacking
Do not use sharp tools when unpacking. Avoid unnecessary impact or shocks. Remove transport protectors and turn the shaft by hand to ensure it rotates freely.
3.2 Handling and Storing the Product
3.2.1 Lifting the Product
WARNING: Risk of crushing feet. Wear protective equipment and use motor eyebolts for lifting. Keep others at a safe distance.
CAUTION: Risk of crushing feet. Ensure eyebolts are secure. Lift the motor carefully to avoid damaging other equipment.
The number of eyebolts and maximum permissible weight are specified by frame size:
| Frame size | Model | Number of eyebolts/ max. permissible weight |
|---|---|---|
| 90, 100 | B, C, D, H | 2 x M8/ 140 kg (1.4 kN) |
| 112, 132 | C, D, F, H | 2 x M10/ 230 kg (2.3 kN) |
| 160, 180 | F, H | 2 x M12/ 340 kg (3.4 kN) |
Frame sizes 71 and 80 do not have eyebolts.
3.2.2 Storage
Store motors in their original packaging in an enclosed, dry, and well-ventilated room. Protect unprotected surfaces with a corrosion inhibitor. For stored motors, turn the shaft monthly to prevent sticking and distribute bearing grease. If stored for over two years, dismantle and check rotating parts; relubricate if necessary.
Storage temperature: -20 to +60 °C.
4. Construction
4.1 Mounting Designations
Motors are available with various mounting designations according to IEC 60034-7. These include flange-mounted (tapped-hole and free-hole) and foot-mounted types, each with specific codes (e.g., IM B 14, IM B 5, IM B 3, IM B 34, IM B 35).
4.2 Drain Holes
MG motors have drain holes in the drive end of the stator housing. In humid environments, open the bottom drain hole to allow condensation to escape. Removing the drain plug changes the motor enclosure class from IP55 to IP44.
4.2.1 Number of Drain Holes
The number and configuration of drain holes vary by mounting type and frame size, as illustrated in diagrams showing motors with one, two, three, or four drain holes closed with plugs.
4.3 Motor Bearings
The bearing type is indicated on the nameplate. Motors in frame sizes 160 and 180 feature lubricating nipples. Lubrication is recommended at commissioning. Lubricating intervals are specified on the mechanical data nameplate. For detailed information, refer to section 10.2 Motor Bearings.
4.4 Balancing
The rotor is dynamically balanced, typically with a half key inserted for cylindrical shafts.
4.5 Cable Entry/Screwed Connection
Motors are supplied without screwed cable entries. The table specifies the number and size of cable entry holes in the terminal box according to EN 50262.
| Frame size | Model | Number x dimensions | Description |
|---|---|---|---|
| 71, 80 | B, C, H | 2 x (M20 x 1.5) | Holes have precast threads and are closed with knock-out cable entries. |
| 90, 100 | B, C, D, H | 4 x M20 | Holes are closed with knock-out cable entries. |
| 112, 132 | C, D, F, H | 4 x M25 | |
| 160, 180 | F, H | 4 x M40 / 2 x M20 |
5. Operating Conditions
5.1 Ambient Temperature and Installation Altitude
Grundfos motors are designed for operation up to 40 °C. Continuous operation is possible up to 60 °C, but with reduced bearing life. Ambient temperature and installation altitude significantly impact motor life. The table shows maximum limits, which cannot be combined (e.g., 60 °C at 3500 m is not simultaneously possible).
| Efficiency class | Max. ambient temperature at full load [°C] | Max. installation altitude above sea level at full load [m] |
|---|---|---|
| NA | +40 | 1000 |
| IE2 | +60 | 3500 |
| IE3 | +60 | 3500 |
Exceeding these values requires reduced load or a higher-rated motor to prevent overheating. A graph illustrates the maximum motor load versus temperature/altitude for different efficiency classes.
Example: For an IE2 motor at 65 °C ambient and 4750 m altitude, the load must be reduced to 83.6% (0.95 x 0.88).
WARNING: Exceeding operating limits voids the warranty and reduces motor life.
5.2 Frequency Converter Operation
All three-phase MG motors with phase insulation can be connected to a frequency converter.
5.2.1 Phase Insulation
MG 71 and 80: These motors lack standard phase insulation and are unsuitable for frequency converter operation due to voltage peaks. Only motors rated 460 V or higher have phase insulation. Using them with frequency converters will cause damage.
MG 90 to 180: These motors have phase insulation and are suitable for frequency converter operation with precautions:
- Supply voltage up to 400 V: Ensure the motor has phase insulation (rated voltage ≥ 460 V).
- Supply voltage above 400 V: Ensure phase insulation and fit a sine-wave filter between the motor and converter.
5.2.2 Acoustic Noise and Voltage Peaks
Frequency converter operation can increase acoustic noise and stress motor insulation due to voltage peaks. Use output or sinusoidal filters to mitigate these effects. A graph shows maximum permissible voltage peaks versus rise time.
5.2.3 Cable Length
The cable length between the motor and frequency converter affects motor load; use a cable meeting the converter supplier's specifications.
5.2.4 Speed
MG motors are generally not suitable for oversynchronous operation (above 60 Hz). Contact Grundfos if required.
6. Mechanical Installation
Installation must be performed by authorized personnel according to local regulations. Ensure the shaft rotates freely.
WARNING: Risk of body injury if testing motor without load; secure shaft keyway.
WARNING: Risk of crushing feet during handling; use protective equipment and eyebolts.
CAUTION: Risk of crushing feet; ensure eyebolts are secure.
6.1 Clearance
Maintain a minimum clearance of 50 mm around the motor for adequate air circulation.
6.2 Terminal Box Positions
For vertically installed motors, the terminal box must not drop more than 10° below the horizontal plane. Position the motor so drain holes allow condensed water to escape.
6.3 Outdoor Installation
Protect motors installed outdoors from water and direct sunlight.
6.4 Foundation
Install motors and pumps on a heavy, rigid foundation capable of absorbing vibrations and shocks. Improper foundations can cause functional faults.
6.5 Alignment
Correct alignment is crucial to prevent bearing issues, vibrations, and shaft fractures.
6.6 Fitting of Coupling Parts and Pulleys
Use appropriate tools and equipment that do not damage motor bearings. Never force coupling parts or pulleys into position; always remove them without pressing against the motor.
7. Electrical Installation
WARNING: Risk of electric shock. Always switch off the power supply before working on the motor and ensure it cannot be accidentally switched on.
7.1 General Information
Verify the motor's voltage and frequency rating on the nameplate match the available power supply. Voltage quality at the motor terminals should be within ±10% of the rated voltage.
WARNING: The motor must be connected to an external main switch.
WARNING: Always use original Grundfos spare parts.
7.1.1 Motor Protection
- Single-phase motors: Equipped with built-in thermal protection against overload.
- Three-phase motors: Require protection by a motor-protective circuit breaker per local regulations. Motors 3.0 kW and above include standard thermal switches (PTC) for overload protection.
WARNING: When servicing motors with thermal switches, ensure the motor cannot restart automatically after cooling.
7.2 Electrical Connection
Electrical installation must be performed by authorized personnel following local regulations. The wiring diagram is located inside the terminal box cover.
WARNING: Risk of electric shock. Switch off power before opening the terminal box or dismantling the motor. Follow the wiring diagram. Do not disturb insulation material inside the box.
The terminal box typically contains six winding terminals and an earth terminal.
WARNING: The motor must be earthed before connecting to the voltage supply.
7.2.1 Single-phase Motor
Connect single-phase motors according to instructions in the terminal box cover.
7.2.2 Three-phase Motor
Three-phase motors can be connected in star (Y) or delta (D) per IEC 60034-8. The nameplate specifies voltage and connection type.
Example: 380-415 D/660-690 Y indicates delta connection for 380-415 V and star for 660-690 V.
8. Starting Up the Product
8.1 Measuring the Insulation Resistance
Measure insulation resistance before start-up and if moisture is suspected. WARNING: Risk of electric shock. Follow safety regulations. Calculate minimum permissible insulation resistance (R) by multiplying rated voltage (kV) by 0.5 megohm/kV. Stop motor if resistance falls below this value.
Example: For 690 V, R must be > 0.35 megohm.
Measure at 25 °C (±15 °C) using a 500 V DC megohmmeter between phase and earth. WARNING: Risk of electric shock during and immediately after measurement; do not touch terminals until de-energized.
If resistance is insufficient, windings may be moist and require oven drying (90 °C for 12-16 hours, then 105 °C for 6-8 hours). Remove drain plugs before heating.
8.2 Direction of Rotation
The default direction of rotation is clockwise when viewed from the drive end, with mains conductors connected per the diagram. This can be changed by switching two conductors. Some motors have a directed fan; ensure rotation matches the motor's stated direction.
9. Operation
CAUTION: Risk of burns from hot surfaces. Wear personal protective equipment.
9.1 Max. Number of Starts per Hour
Refer to Appendix A for details.
10. Service
Service must be performed by qualified persons according to IEC 60079-19 and EN 50110-1.
WARNING: Risk of electric shock. Switch off power before any work. Follow wiring diagrams. Ensure motor is earthed. Do not remove insulation material. Ensure motor cannot restart automatically after cooling.
WARNING: Risk of crushing feet during handling. Wear protective equipment and use eyebolts.
CAUTION: Risk of crushing feet; ensure eyebolts are secure.
WARNING: Risk of body injury from ejected objects after assembly; ensure no loose items are present. Secure shaft keyway if testing without load.
CAUTION: Risk of burns from hot surfaces. Wear personal protective equipment.
10.1 Motor
Inspect motors regularly based on the environment. Keep motors clean for adequate ventilation. In standard motors, open the drain hole to allow condensed water to escape.
10.2 Motor Bearings
WARNING: Risk of electric shock. Do not remove insulation material inside the motor. Avoid impacts or shocks to bearings.
10.2.1 Motors without Lubricating Nipples
Bearings are greased for life, with an expected life of at least 18,000 operating hours at 40 °C. Higher temperatures reduce life.
Bearing Grease: Must meet DIN 51825, K3N or better. Specifications: 50 cSt (mm²/s) at 40 °C, 8 cSt (mm²/s) at 100 °C. Grease filling rate: 30-40%.
10.2.2 Motors with Lubricating Nipples
Lubricate with high-temperature grease specified on the nameplate. Lubricating intervals are on the nameplate. Dismantle bearings after five relubrications for inspection. For seasonal operation, lubricate before storage. Failure to observe intervals reduces bearing life.
Reduced Lubricating Interval: Apply for dirty/dusty environments (factor 0.75) or very moist environments (factor 0.9). Multiply factors for combined conditions.
Grease Type and Quantity: Refer to the motor nameplate. Never mix grease types.
10.3 Service Documentation
Available at www.grundfos.com > Grundfos Product Center > Service. Contact your nearest Grundfos company for questions.
11. Fault Finding
WARNING: Risk of electric shock. Switch off power before fault finding. Service must be by qualified persons.
The table below covers common faults and their causes. Contact Grundfos for unlisted faults.
| Fault | Cause |
|---|---|
| Motor does not start. | Power supply disconnected. Fuses blown. Automatic circuit breakers cut out. Motor-protective circuit breaker tripped. Thermal protection tripped. Contacts of motor-protective circuit breaker or magnet coil defective. Control circuit defective. Blocked rotor. Motor defective. |
| Motor-protective circuit breaker trips immediately when supply is switched on. | A fuse blown. Contacts of motor-protective circuit breaker defective. Blocked rotor. |
| Motor-protective circuit breaker trips occasionally. | Cable connection loose or faulty. Motor winding defective. Motor-protective circuit breaker setting is too low. Mains voltage periodically too low. Voltage asymmetry. |
12. Technical Data
Specific technical data such as weight, enclosure class, dimensional sketches, sound pressure level, and winding resistances can be found on the motor nameplate, in the Grundfos Product Center, or in specific product information documents.
13. Disposing of the Product
Dispose of this product or its parts in an environmentally sound manner. Use public or private waste collection services. If not possible, contact the nearest Grundfos company. The crossed-out wheelie bin symbol ?️ indicates separate disposal from household waste. This helps protect the environment and human health. For end-of-life information, visit www.grundfos.com/product-recycling.
Appendix A
A.1. Appendix: Maximum Number of Starts per Hour
The table below specifies the maximum number of starts per hour for 2-pole and 4-pole motors by type designation.
| 2-pole motors | 4-pole motors | ||
|---|---|---|---|
| Type designation | Maximum number of starts per hour | Type designation | Maximum number of starts per hour |
| MG 71A2 | 250 | MG 71A4 | 250 |
| MG 71B2 | MG 71B4 | ||
| MG 80A2 | MG 80A4 | ||
| MG 80B2 | MG 80B4 | ||
| MG 90SA2 | MG 90SA4 | ||
| MG 90SB2 | MG 90SB4 | ||
| MG 90LA2 | MG 90LA4 | ||
| MG 90LB2 | 100 | MG 90LB4 | 100 |
| MG 90LC2 | MG 90LC4 | ||
| MG 100LA2 | MG 100LA4 | ||
| MG 100LC2 | MG 100LB4 | ||
| MG 112MB2 | MG 100LC4 | ||
| MG 112MC2 | 50 | MG 112MB4 | 50 |
| MG 132SB2 | MG 112MC4 | ||
| MG 132SC2 | MG 132MB4 | ||
| MG 132SD2 | MG 132SB4 | ||
| MG 160MB2 | 40 | MG 132SC4 | 40 |
| MG 160MD2 | MG 160MB4 | ||
| MG 160LB2 | MG 160LB4 | ||
| MG 180MB2 | |||
Dimensional Sketches
Diagrams illustrating various motor mounting types (Foot-mounted IM B 3, Foot-mounted with free-hole flange IM B 35/IM B5/V1, Foot-mounted with tapped-hole flange IM B 34/IM B14/V18) are provided. These sketches show key dimensions labeled with letters (e.g., L, EB, GA, etc.), which are detailed in the tables on pages 16-17.
Declarations of Conformity
This document includes EU Declarations of Conformity for Grundfos MG/ML products, confirming compliance with relevant EU directives and regulations. Additional declarations are provided for Moroccan, UK, and Ukrainian conformity, referencing specific laws, orders, and standards. These declarations are valid only when accompanying Grundfos instructions.
