Grundfos MG Motor Installation and Operating Instructions
This document provides comprehensive instructions for the installation and operation of Grundfos MG motors.
1. Symbols Used in This Document
Warning: Indicates a hazardous situation which, if not avoided, could result in death or serious injury.
Caution: Indicates a hazardous situation which, if not avoided, could result in minor or moderate injury.
Note: Notes or instructions that make the job easier and ensure safe operation.
2. Introduction
These installation and operating instructions apply to Grundfos MG motors. MG motors can be used within the framework of IEC 60034.
2.1 Application
MG motors are suitable for various applications within the framework of IEC 60034.
| Model | Power range [kW] | IEC frame size | |||
|---|---|---|---|---|---|
| Phase | 2-pole | 4-pole | 2-pole | 4-pole | |
| B | 0.25-2.2 | 0.18-1.1 | 71-90 | 71-90 | |
| C | 0.37-11 | 0.25-5.5 | 71-132 | 71-132 | |
| D | 1.1-11 | 1.1-4.0 | 90-160 | 90-112 | |
| F | 7.5 - 22 | 5.5-15 | 132-180 | 132-160 | |
| H | 0.75-22 | 0.75-15 | 80-180 | 90-160 |
For model designation, see section 4.2 Type key.
3. Delivery and Handling
3.1 Delivery
Upon receipt, check the motor for external damage. Contact the shipping agent immediately if damage is found. Verify that all nameplate data are correct and that the winding is connected according to the wiring diagram.
3.1.1 Unpacking
Caution: Do not use sharp tools when unpacking the motor. Avoid unnecessary impact and shocks.
Remove transport protectors. Turn the shaft by hand to ensure it rotates freely.
3.2 Handling
Lift the motor using the eye bolts. Avoid damaging additional equipment and cables.
The table below shows the number of eye bolts and the maximum permissible weight for different frame sizes.
| Frame size | Model | Number of eye bolts/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 have no eye bolts.
3.2.2 Storage
Store motors in their original packaging in an enclosed, dry, and well-ventilated room. Treat unprotected machine surfaces with a corrosion inhibitor. Turn the shaft by hand at least once a month to prevent it from seizing.
Storage temperature: -20 °C to +60 °C.
4. Identification
4.1 Nameplate
The motor has two nameplates: one for electrical data (50 and 60 Hz) and one for mechanical data (irrespective of frequency). The nameplates are located on the side of the motor.
4.2 Type key
The type designation is stated on the nameplate. An example of the type key is provided:
Example: MG 132 S B 2-38 FF 265 -H 3
This key indicates:
- Frame size
- Length of stator core
- Number of poles
- Diameter of shaft end
- Flange version
- Pitch circle diameter
- Model
- Efficiency class
5. Construction
5.1 Mounting designations
This section details the various mounting designations according to IEC 60034-7, Code I and Code II.
5.2 Drain holes
MG motors have drain holes in the drive end of the stator housing. If the motor is installed in a humid environment, open the bottom drain hole to allow water to escape.
Caution: Removing the drain plug changes the enclosure class from IP55 to IP44.
5.2.1 Number of drain holes
Diagrams illustrate the number of drain holes for different frame sizes and flange types.
5.3 Motor bearings
The motor bearing type is stated on the nameplate. Motors with lubricating nipples (frame sizes 160 and 180) require lubrication from the factory.
5.4 Balancing
The rotor is dynamically balanced with a half key inserted as standard.
5.5 Cable entry/screwed connection
Motors are supplied without screwed cable entries. The table below shows 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) | Pre-cast threads, closed with knock-out cable entries. |
| 90, 100 | B, C, D, H | 4 x M20 | Holes closed with knock-out cable entries. |
| 112, 132 | C, D, F, H | 4 x M25 | |
| 160, 180 | F, H | 4 x M40 | Holes closed with knock-out cable entries. |
6. Operating conditions
6.1 Ambient temperature and installation altitude
Grundfos MG motors are designed for operation up to 40 °C. Continuous operation is possible up to 60 °C, but may reduce bearing life. Ambient temperature and installation altitude affect motor life. The table shows maximum values, but combined maximums are not applicable simultaneously.
| 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 may lead to overheating and reduced motor life. Load reduction or a higher rated output motor may be necessary.
Figure 1 illustrates the motor output in relation to temperature and installation altitude.
6.2 Frequency converter operation
All three-phase MG motors with phase insulation can be connected to a frequency converter. Motors without phase insulation (MG 71 and 80) are not suitable for frequency converter operation unless they have a rated voltage of 460 V or higher.
Caution: Frequency converter operation of MG motors without phase insulation will cause damage.
For MG motors, frame sizes 90 to 180, with phase insulation, follow these precautions:
- Supply voltage up to 400 V: Ensure the motor has phase insulation (rated voltage ≥ 460 V).
- Supply voltage above 400 V: Ensure the motor has phase insulation (rated voltage ≥ 460 V) and fit a sine-wave filter between the motor and the frequency converter.
Frequency converter operation can increase acoustic noise and stress the motor insulation system due to voltage peaks. Figure 2 shows maximum permissible voltage peaks.
7. Mechanical installation
Installation must be performed by authorized personnel according to local regulations.
7.1 Clearance
A minimum clearance of 50 mm over and around the motor is required for sufficient air circulation.
7.2 Terminal box positions
For vertically installed motors, the terminal box must not be more than 10° below the horizontal plane. Ensure drain holes are positioned to allow condensed water to escape.
7.3 Outdoor installation
Protect outdoor installations against water and sunshine.
7.4 Foundation
Install the motor and pump on a rigid and stable foundation capable of absorbing vibrations and shocks. Failure to do so may result in functional faults.
7.5 Alignment
Correct alignment is crucial to prevent bearing issues, vibrations, and shaft fractures.
7.6 Fitting of coupling parts and pulleys
Use appropriate equipment and tools that do not damage motor bearings. Never knock coupling parts or pulleys into position.
8. Electrical installation
Warning: Ensure the power supply is switched off before starting electrical installation.
8.1 General information
Verify that the motor's operating voltage and frequency 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 mains switch.
8.1.1 Motor protection
Single-phase motors have built-in thermal protection. Three-phase motors require protection via a motor-protective circuit breaker according to local regulations. Motors from 3.0 kW are equipped with thermal switches (PTC) for overload protection.
Warning: Ensure motors with thermal switches cannot start automatically after cooling during repair.
8.2 Electrical connection
Electrical installation must be carried out by authorized personnel according to local regulations. The wiring diagram is in the terminal box cover.
Warning: Switch off the power supply before opening the terminal box or dismantling the motor.
Warning: The motor must be earthed. Connect the motor to the voltage supply only after earthing is completed.
8.2.1 Single-phase motor
Connect single-phase motors according to the instructions in the terminal box cover.
8.2.2 Three-phase motor
Three-phase motors can be connected in star (Y) or delta (D) according to IEC 60034-8. Voltage and connection details are on the nameplate.
9. Start-up
9.1 Measuring the insulation resistance
Measure insulation resistance before start-up, especially if moisture is suspected. Follow safety regulations (EN 50110-1) and equipment manuals.
Calculate the minimum permissible insulation resistance (R) by multiplying the rated voltage (kV) by 0.5 megohm/kV.
Warning: Do not touch terminals until windings are de-energised. Stop using the motor if insulation resistance falls below the calculated value.
Procedure:
- Connect the megaohmmeter between phase and earth using a 500 V DC measuring voltage.
- Read the value on the megaohmmeter.
If the minimum insulation resistance is not attained, the windings may be too moist and require oven drying at 90 °C for 12-16 hours, followed by 105 °C for 6-8 hours.
Note: Remove any drain plugs before heating.
9.2 Direction of rotation
The direction of rotation is clockwise when viewed from the motor drive end, assuming mains conductors are connected per the terminal box cover diagram. The direction can be changed by switching two random mains conductors.
Caution: Some MG motors have a directed fan. Ensure the direction of rotation matches the motor's stated direction.
10. Operation
Warning: Motor surfaces can become very hot, potentially causing burns.
10.1 Max. number of starts per hour
Refer to page 9 for maximum number of starts per hour.
11. Maintenance
11.1 Motor
Inspect the motor regularly, depending on the operating environment. Keep the motor clean to ensure adequate ventilation. Dusty environments require more frequent cleaning and inspection.
For standard motors, open the bottom drain hole to allow condensed water to escape.
11.2 Motor bearings
Motors without lubricating nipples: Bearings are greased for life, with an expected life of at least 18,000 operating hours at up to 40 °C ambient temperature. Higher temperatures reduce bearing life.
Bearing grease: Use grease conforming to DIN 51825, K3N or better, with specific viscosity at 40 °C and 100 °C. Grease filling rate should be 30-40%.
Motors with lubricating nipples: Lubricate bearings with high-temperature grease as specified on the nameplate. Follow lubricating intervals indicated on the plate. Dismantle and check bearings after five relubrications. Relubricate motors with lubricating nipples annually if used seasonally.
Reduced lubricating interval: Reduce the interval by a factor of 0.75 for dirty/dusty environments and by 0.9 for very moist environments. Multiply factors for combined conditions.
Note: Never mix different types of grease.
12. Technical data
Refer to the motor nameplate, WinCAPS, or WebCAPS for specific technical data including:
- Weight
- Enclosure class
- Dimensional sketches (see page 10)
- Sound pressure level
- Winding resistances
13. Fault finding
Warning: Switch off the power supply before starting fault finding. Ensure the power supply cannot be accidentally switched on.
Motor service and fault finding should be performed by qualified personnel.
The table below lists common faults and their causes. Contact Grundfos if the fault is not listed.
| Fault | Cause |
|---|---|
| Motor does not start. | a) Power supply disconnected. |
| b) Fuses blown. | |
| c) Automatic circuit breakers cut out. | |
| d) Motor-protective circuit breaker tripped. | |
| e) Thermal protection tripped. | |
| f) Contacts of motor-protective circuit breaker or magnet coil defective. | |
| g) Control circuit defective. | |
| h) Blocked rotor. | |
| i) Motor defective. | |
| Motor-protective circuit breaker trips immediately when supply is switched on. | a) A fuse blown. |
| b) Contacts of motor-protective circuit breaker defective. | |
| c) Blocked rotor. | |
| d) Cable connection loose or faulty. | |
| Motor-protective circuit breaker trips occasionally. | a) Motor winding defective. |
| b) Motor-protective circuit breaker setting is too low. | |
| c) Mains voltage periodically too low. | |
| d) Voltage asymmetry. |
14. Service
All repairs must be carried out in accordance with IEC 60079-19. Observe EN 50110-1 provisions.
14.1 Motor bearings
Take care when replacing motor bearings. Caution: Do not expose bearings to impacts or shocks.
14.2 Service documentation
Service documentation is available on www.grundfos.com > WebCAPS > Service. Contact your nearest Grundfos company for assistance.
15. Disposal
Dispose of this product or its parts in an environmentally sound manner using public or private waste collection services. If not possible, contact the nearest Grundfos company or service workshop.
Appendix
Maximum number of starts per hour
Tables list the maximum number of starts per hour for 2-pole and 4-pole motors by type designation.
Dimensional sketches
Diagrams illustrate dimensional sketches for various foot-mounted and flange-mounted motor configurations.
