Grundfos SP User manual

GRUNDFOS INSTRUCTIONS
SP
Stainless steel submersible pumps
4", 6", 8", and 10"
Installation and operating instructions

2

3
Table of contents
SP
English (US)
Installation and operating instructions . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
Français (CA)
Notice d'installation et de fonctionnement . . . . . . . . . . . . . . . . . . . . . . . 45
Español (MX)
Instrucciones de instalación y operación . . . . . . . . . . . . . . . . . . . . . . . . 86
Appendix 1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 128
Annexe 1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 130
Anexo 1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 132

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English (US)
English (US) Installation and operating instructions
Original installation and operating
instructions
CONTENTS
Page
1. Limited warranty 5
2. Symbols used in this document 5
3. Product description 6
3.1 Introduction 6
3.2 Applications 6
3.3 Features and benefits 6
3.4 Type key 6
4. Delivery, handling and storage 6
4.1 Delivery 6
4.2 Handling 6
4.3 Storage 7
5. Operating conditions 7
6. Installation 7
6.1 Pre-installation checklist 7
6.2 Positional requirements 8
6.3 Preparation 9
6.4 Removing and fitting the cable guard 11
6.5 Splicing the motor cable 11
6.6 Riser pipe 12
6.7 Electrical and variable-frequency
drive information 14
7. Startup 22
7.1 Startup with three-phase motors 22
8. Operation 24
8.1 Minimum flow rate 24
8.2 Soft starter 25
8.3 Maintenance and service 25
9. Troubleshooting 25
9.1 Preliminary tests 26
9.2 Checking pump performance 27
9.3 Troubleshooting chart 28
10. Technical data 32
10.1 Motor cooling requirements 32
10.2 Guide for engine-driven generators
in submersible pump applications 33
10.3 Transformer capacity required for
three-phase submersible motors 34
10.4 Submersible drop cable selection
charts (60 Hz) 34
10.5 Approvals 40
10.6 Electrical data 41
11. Disposal 44
WARNING
Prior to installation, read these
installation and operating instructions.
Installation and operation must
comply with local regulations and
accepted codes of good practice.
Keep this booklet with the pump for
future reference and information
regarding its operation.
WARNING
The installation of this product
requires experience with and
knowledge of the product.
Persons with reduced physical,
sensory or mental capabilities must
not use this product, unless they are
under supervision or have been
instructed in the use of the product by
a person responsible for their safety.
Children must not use or play with this
product.

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English (US)
1. Limited warranty
Products manufactured by GRUNDFOS PUMPS
CORPORATION (Grundfos) are warranted to
the original user only to be free of defects in
material and workmanship for a period of 24
months from date of installation, but not more
than 30 months from date of manufacture.
Grundfos' liability under this warranty shall be
limited to repairing or replacing at Grundfos'
option, without charge, FOB Grundfos' factory or
authorized service station, any product of
Grundfos' manufacture. Grundfos will not be
liable for any costs of removal, installation,
transportation, or any other charges which may
arise in connection with a warranty claim.
Products which are sold but not manufactured
by Grundfos are subject to the warranty
provided by the manufacturer of said products
and not by Grundfos' warranty. Grundfos will not
be liable for damage or wear to products caused
by abnormal operating conditions, accident,
abuse, misuse, unauthorized alteration or repair,
or if the product was not installed in accordance
with Grundfos' printed installation and operating
instructions.
To obtain service under this warranty, the
defective product must be returned to the
distributor or dealer of Grundfos' products from
which it was purchased together with proof of
purchase and installation date, failure date, and
supporting installation data. Unless otherwise
provided, the distributor or dealer will contact
Grundfos or an authorized service station for
instructions. Any defective product to be
returned to Grundfos or a service station must
be sent freight prepaid; documentation
supporting the warranty claim and/or a Return
Material Authorization must be included if so
instructed.
GRUNDFOS WILL NOT BE LIABLE FOR ANY
INCIDENTAL OR CONSEQUENTIAL
DAMAGES, LOSSES, OR EXPENSES ARISING
FROM INSTALLATION, USE, OR ANY OTHER
CAUSES. THERE ARE NO EXPRESS OR
IMPLIED WARRANTIES, INCLUDING
MERCHANTABILITY OR FITNESS FOR A
PARTICULAR PURPOSE, WHICH EXTEND
BEYOND THOSE WARRANTIES DESCRIBED
OR REFERRED TO ABOVE.
Some jurisdictions do not allow the exclusion or
limitation of incidental or consequential
damages and some jurisdictions do not allow
limit actions on how long implied warranties may
last. Therefore, the above limitations or
exclusions may not apply to you. This warranty
gives you specific legal rights and you may also
have other rights which vary from jurisdiction to
jurisdiction.
2. Symbols used in this document
WARNING
If these safety instructions are not
observed, it may result in personal
injury.
WARNING
If these instructions are not observed,
it may lead to electric shock with
consequent risk of serious personal
injury or death.
Caution
CAUTION
If these safety instructions are not
observed, it may result in malfunction
or damage to the equipment.
Note
Notes or instructions that make the
job easier and ensure safe operation.

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English (US)
3. Product description
3.1 Introduction
Your Grundfos SP submersible pump is of the
highest quality. Combined with proper
installation, your Grundfos pump will give you
many years of reliable service.
To ensure the proper installation of the pump,
carefully read the complete manual before
attempting to install the pump.
3.2 Applications
Grundfos SP submersible pumps are suitable for
the following applications:
• groundwater supply to waterworks
• irrigation in horticulture and agriculture
• groundwater lowering (dewatering)
• pressure boosting
• industrial applications
• domestic water supply.
3.3 Features and benefits
• State-of-the-art hydraulics provide high
efficiency and low operating costs
• 100 % stainless steel components inside and
outside for long service life
• sand resistant
• resistant to aggressive water
• monitoring, protection, and communication
via protection unit MP 204, and GO remote
control.
3.4 Type key
4. Delivery, handling and storage
4.1 Delivery
Examine the components carefully to make sure
no damage has occurred to the pump end,
motor, cable or control box during shipment.
4.2 Handling
Keep the pump in the shipping carton until it is
ready to be installed. The shipping carton is
specially designed to protect it from damage.
During unpacking and prior to installation, make
sure that the pump is not dropped or
mishandled.
Do not expose the pump to unnecessary impact
and shocks.
The motor is equipped with a power cable.
You will find a loose nameplate with an adhesive
backing with the pump. If the nameplate is
blank, complete it in pen and attach it to the
control box.
Example 475 S 500 - 5 - A B
Rated flow rate in gpm
Type range
Stainless steel parts of
material
S = AISI 304
N = AISI 316
R = AISI 904L
Hp of motor
Number of impellers
First reduced-diameter impeller (A, B or C)
Second reduced-diameter impeller (A, B or C)
Caution
CAUTION
Keep the pump in the shipping carton
until it is placed in the vertical position
during installation.
Handle the pump with care.
Caution
CAUTION
Never use the power cable to support
the weight of the pump.
Note
Fix the extra nameplate supplied with
the pump at the installation site.

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English (US)
4.3 Storage
4.3.1 Storage temperature
Pump: -4 - +140 °F (-20 - +60 °C).
Motor: -4 - +158 °F (-20 - +70 °C).
Store the motors in a closed, dry and well
ventilated room.
Do not expose the pump to direct sunlight.
If the pump has been unpacked, store it
horizontally, adequately supported, or vertically
to prevent misalignment. Make sure that the
pump cannot roll or fall over.
During storage, the pump can be supported as
shown in fig. 1.
Fig. 1 Pump position during storage
4.3.2 Frost protection
If the pump has to be stored after use, it must be
stored on a frost-free location, or the motor
liquid must be frost-proof.
5. Operating conditions
6. Installation
Install products in accordance with the local
code of the authority having jurisdiction.
Installation must be carried out by a qualified
person.
6.1 Pre-installation checklist
Make the following checks before beginning
installation:
• condition of the well
• condition of the water
• installation depth
• power supply
• cable type.
These checks are all critical for the proper
installation of this submersible pump.
Caution
CAUTION
If MMS motors are stored, the shaft
must be turned by hand at least once
a month. If a motor has been stored
for more than one year before
installation, the rotating parts of the
motor must be dismantled and
checked before use.
TM00 1349 2495
Flow rate, Q: Up to 1400 gpm
(318 m3/h)
Head, H: Up to 2657 ft
(810 m)
Liquid
temperature:
32-140 °F
(0-60 °C)
Maximum
submersible
depth:
MS 402 492 ft (150 m)
(213 psi)
MS 4000 1969 ft (600 m)
(852 psi)
MS 6000 1969 ft (600 m)
(852 psi)
All MMS 1969 ft (600 m)
(852 psi)
WARNING
Risk of electric shock. Do not remove
cord and strain relief. Do not connect
conduit to pump.

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English (US)
6.1.1 Condition of the well
If the pump is to be installed in a new well, make
sure that the well is fully developed and bailed
or blown free of cuttings, drillings and sand. The
stainless steel construction of the Grundfos
submersible pump makes it resistant to
abrasion; however, no pump, made of any
material, can forever withstand the destructive
wear that occurs when constantly pumping
sandy water.
If this pump is used to replace an oil-filled
submersible or oil-lubricated line-shaft turbine
pump in an existing well, the well must be blown
or bailed clear of oil.
Determine the maximum depth of the well, and
the draw-down level at the pump's maximum
capacity. Use this data for pump selection and to
determine installation depth.
Check the inside diameter of the well casing to
ensure that it is larger than the size of the pump
and motor.
6.2 Positional requirements
Depending on the motor type, the pump can be
installed either vertically or horizontally. A
complete list of motor types suitable for
horizontal installation is shown in section
6.2.1 Motors suitable for horizontal installation.
If the pump is installed horizontally, make sure
that the outlet port never falls below the
horizontal plane. See fig. 2.
Fig. 2 Positional requirements
If the pump is installed horizontally, e.g. in a
tank, we recommend that you fit it in a flow
sleeve.
6.2.1 Motors suitable for horizontal
installation
WARNING
Leave the inlet screen in place if the
pump installation is accessible to
human touch.
TM00 1355 5092
Allowed
Not
allowed
Motor
Output power
60 Hz
Output power
50 Hz
[Hp (kW)] [Hp (kW)]
MS 0.5 - 40
(0.37 - 30) All
MMS6 50-60
(37 - 44.7)
5-50
(3.7 - 37)
MMS 8000 30-150
(22-112)
30-150
(22-112)
MMS 10000 100-250
(75-190)
100-250
(75-190)
Caution
CAUTION
During operation, the suction
interconnector of the pump must
always be completely submerged in
the liquid. Make sure that the NPSH
values are fulfilled.
WARNING
If the pump is used for pumping hot
liquids of 104-140 °F (40-60 °C),
make sure that persons cannot come
into contact with the pump and the
installation, e.g. by installing a guard.

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English (US)
6.2.2 Pumped liquids
Submersible pumps are designed for pumping
the following liquids:
• clear and cold water that is free of air and
gasses
• clean, thin, non-explosive liquids without
solid particles or fibers.
Decreased pump performance and life
expectancy can occur if the water is not cold and
clear or contains air and gasses.
See the flow velocity table in section 10.1 Motor
cooling requirements.
When the pump and motor are used for pumping
water above the rated temperatures of the
motor, pay special attention to minimum water
flow past the motor for cooling. Water
temperature that exceeds motor rated
temperature directly shortens the motor life.
The Grundfos stainless steel submersible pump
is highly resistant to the normal corrosive
environment found in some water wells. If water
well tests show that the water has an excessive
or unusual corrosive quality, or exceeds the
motor temperature rating, contact your Grundfos
representative for information concerning
specially designed pumps for these applications.
6.3 Preparation
6.3.1 Checking of liquid in motor
The MS submersible motors are factory-filled
with SML-3 liquid, which is frost-proof down to -4
°F (-20 °C).
Carry out refilling of liquid as described below.
6.3.2 Grundfos submersible motors MS 4000
and MS 402
The filling hole for motor liquid is placed in the
following positions:
MS 4000: In the top of the motor.
MS 402: In the bottom of the motor.
1. Position the submersible pump as shown in
fig. 3.
Make sure that the filling screw is at the
highest point of the motor.
2. Remove the screw from the filling hole.
3. Inject liquid into the motor with the filling
syringe as shown in fig. 3until the liquid runs
back out of the filling hole.
4. Replace the screw in the filling hole and
tighten securely before changing the position
of the pump.
Tor qu es :
MS 4000: 2.2 ft-lbs (3.0 Nm).
MS 402: 1.5 ft-lbs (2.0 Nm).
The submersible pump is now ready for
installation.
Fig. 3 Pump position during filling, MS
4000 and MS 402
Caution
CAUTION
This pump has been tested for use
with water only. Water temperature
should not exceed rated motor
temperature. SP pumps can
withstand water temperatures up to
140°F (60°C). Water temperature that
exceeds motor rated temperature
directly shortens the motor life. The
suitability of this pump for use with
liquids other than water is the
responsibility of the end user.
Flow rate, Q: 0.44 - 1475 gpm (0.1 - 335 m3/h)
Head, H: Maximum 2657 ft (810 m)
WARNING
Before starting work on the pump,
make sure that the power supply has
been switched off and that it cannot
be accidentally switched on.
Note
Check the level of the liquid in the
motor, and refill the motor, if required.
Use clean water.
Caution
CAUTION
If frost protection is required, use
special Grundfos liquid to refill the
motor. Otherwise clean water may be
used for refilling. However, never use
distilled water.
TM00 6423 0606
MS 4000 MS 402

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English (US)
6.3.3 Grundfos submersible motors, MS
6000C
• If the motor is delivered from stock, the liquid
level must be checked before the motor is
fitted to the pump. See fig. 4.
• On pumps delivered directly from Grundfos,
the liquid level has already been checked.
• In the case of service, the liquid level must
be checked. See fig. 4.
Filling procedure:
The filling hole for motor liquid is placed in the
top of the motor.
1. Position the submersible pump as shown in
fig. 4.
Make sure that the filling screw is at the
highest point of the motor.
2. Remove the screw from the filling hole.
3. Inject liquid into the motor with the filling
syringe (see fig. 4) until the liquid runs back
out of the filling hole.
4. Replace the screw in the filling hole and
tighten securely before changing the position
of the motor.
Torque: 2.2 ft-lbs (3.0 Nm).
The submersible pump is now ready for
installation.
Fig. 4 Motor position during filling, MS
6000C
6.3.4 Grundfos submersible motors, MMS6,
MMS 8000, and MMS 10000
Filling procedure:
1. Place the motor at a 45 ° angle with the top
of the motor upwards. See fig. 5.
2. Unscrew the plug A and place a funnel in the
hole.
3. Pour tap water into the motor until the motor
liquid inside the motor starts running out at
A.
4. Remove the funnel and refit the plug A.
The submersible pump is now ready for
installation.
Fig. 5 Motor position during filling, MMS
TM05 0949 1911
45°
Caution
CAUTION
Do not use motor liquid as it contains
oil.
Caution
CAUTION
Before fitting the motor to a pump
after a long period of storage,
lubricate the shaft seal by adding a
few drops of water and turning the
shaft.
TM03 0265 3605
45°
A

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English (US)
6.3.5 Installation depth
Make sure that the installation depth of the
pump is always at least 3 ft (1 m) below the
maximum draw-down level of the well. For flow
rates exceeding 100 gpm (22.7 m3/h), refer to
performance curves for recommended minimum
submergence.
Never install the pump so that the bottom of the
motor is lower than the top of the well screen or
within five feet of the well bottom.
If the pump is to be installed in a lake, pond,
tank or large diameter well, make sure that the
water velocity passing over the motor is
sufficient to ensure proper motor cooling. The
minimum recommended water flow rates
ensuring proper cooling are listed in section
10.1 Motor cooling requirements.
6.3.6 Power supply
Check the motor voltage, phase number and
frequency indicated on the motor nameplate
against the actual power supply.
6.3.7 Power cable type
The power cable used between the pump and
control box or control panel must be approved
for submersible pump applications. Conductors
may be solid or stranded. The cable may consist
of individually insulated conductors twisted
together, insulated conductors molded side by
side in one flat cable or insulated conductors
with a round overall jacket.
The conductor insulation must be type RW,
RUW, TW, TWU or equivalent and must be
suitable for use with submersible pumps. An
equivalent Canadian Standards Association
(CSA) certified cable may also be used. See
section 10.4 Submersible drop cable selection
charts (60 Hz) for recommended cable lengths.
6.4 Removing and fitting the cable
guard
If the cable guard is attached with screws,
remove the screws to loosen the cable guard. To
fit the cable guard on the pump, tighten the
screws to fit the cable guard securely to the
pump.
6.5 Splicing the motor cable
If the splice is carefully made, it will work as well
as any other portion of the cable, and will be
completely watertight. Grundfos recommends
that you use a heat shrink splice kit. Make the
splice in accordance with the kit manufacturer's
instructions. Typically a heat shrink splice can
be made as follows:
1. Examine the motor cable and the
submersible drop cable carefully for damage.
2. Cut the motor leads off in a staggered
manner. Cut the ends of the drop cable so
that the ends match up with the motor leads.
See fig. 6. On single-phase motors, be sure
to match the colors.
3. Strip back and trim off 1/2 inch of insulation
from each lead, making sure to scrape the
wire bare to obtain a good connection. Be
careful not to damage the copper conductor
when stripping off the insulation.
4. Slide the heat shrink tubing on to each lead.
Insert a properly sized "Sta-Kon" type
connector on each lead, making sure that
lead colors are matched. Using "Sta-Kon"
crimping pliers, indent the lugs. See fig. 7.
Be sure to squeeze hard on the pliers,
particularly in the case of a large cable.
5. Center the heat shrink tubing over the
connector. Using a propane torch, lighter, or
electric heat gun, uniformly heat the tubing
starting first in the center working towards
the ends. See fig. 8.
6. Continue to apply the heat to the tubing
taking care not to let the flame directly
contact the tubing. When the tubing shrinks
and the sealant flows from the ends of the
tubing, the splice is complete. See fig. 9.
Caution
CAUTION
When the cable guard has been fitted,
make sure that the pump chambers
are aligned.
Note
A good cable splice is critical to
proper operation of the submersible
pump and must be done with extreme
care.

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English (US)
Fig. 6 Cutting and stripping the motor
leads
Fig. 7 Crimping the connectors
Fig. 8 Applying heat to the connector
Fig. 9 Completed splices
6.6 Riser pipe
6.6.1 If an adapter is required
We recommend that you first install the riser
pipe to the pipe adapter. Then install the riser
pipe with the adapter to the pump outlet port.
Use a back-up wrench when attaching the riser
pipe to the pump. Make sure that the pump is
gripped only by the flats on the top of the outlet
chamber. The body of the pump, cable guard or
motor must not be gripped under any
circumstance.
Fig. 10 Pipe adapters
TM05 0032 0611
TM05 0033 0611
TM05 0034 0611
TM05 0035 0611
Note
Make sure that the riser pipe or hose
are properly sized and selected on
the basis of estimated flow rates and
friction-loss factors.
TM05 0036 2013
475S 385S
Riser pipe
Pipe adapters
Pump outlet
or

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English (US)
6.6.2 If a steel riser pipe is used
We recommend that you always use steel riser
pipes with the large submersible pumps. Use an
approved pipe thread compound on all joints.
Make sure the joints are adequately tightened in
order to prevent the joints from coming loose
when the motor starts and stops.
When tightened, make sure that the first section
of the riser pipe does not come in contact with
the check valve retainer.
After the first section of the riser pipe has been
attached to the pump, clamp the lifting wire to
the pump, if there is a provision on the pump for
a lifting wire. If not, clamp the lifting wire to the
first section of the riser pipe.
When raising the pump and riser pipe section to
upright position, be careful not to place bending
stress on the pump by picking it up by the pump
end only.
Make sure that the power cables are not cut or
damaged in any way when the pump is being
lowered in the well.
Fasten the submersible drop cable to the riser
pipe at frequent intervals to prevent sagging,
looping or possible cable damage. Nylon cable
clips or waterproof tape may be used. Protect
the cable splice by securing it with clips or tape
just above and below the splice.
6.6.3 If a plastic or flexible riser pipe is used
We recommend that you use plastic type riser
pipes only with the smaller domestic
submersible pumps.
Contact the pipe manufacturer or representative
to ensure that the pipe type and physical
characteristics are suitable for this use.
Use the correct joint compound recommended
by the pipe manufacturer. In addition to making
sure that joints are securely fastened, we
recommend that you use a torque arrester when
using a plastic pipe.
Do not connect the first plastic or flexible riser
pipe section directly to the pump. Always attach
a metallic nipple or adapter into the valve casing
at the top of the pump. When tightened, make
sure that the threaded end of the nipple or
adapter does not come in contact with the check
valve retainer.
Fasten the submersible drop cable to the riser
pipe at frequent intervals to prevent sagging,
looping and possible cable damage. Grundfos
nylon cable clips or waterproof tape may be
used. Protect the cable splice by securing it with
Grundfos cable clips or tape just above each
joint.
Check valves
Always install a check valve at the top of the
well. In addition, for installations deeper than
200 feet (61 m), install check valves at no more
than 200 ft (61 m) intervals.
Protect the well from contamination
To protect against surface water entering the
well and contaminating the water source, make
sure that the well is finished off above grade and
that a locally approved well seal or pitless
adapter unit is utilized.
Caution
CAUTION
When a plastic riser pipe is used, we
recommend that you attach a safety
cable to the pump to lower and raise
it.
Note
Important: Plastic and flexible pipes
tend to stretch under load. Take this
stretching into account when securing
the cable to the riser pipe. Leave 3 to
4 inches of slack between clips or
taped points to allow for this
stretching. This tendency for plastic
and flexible pipe to stretch also
affects the calculation of the pump
installation depth. As a general rule,
you can estimate that plastic pipe
stretches to approximately 2 % of its
length. For example, if you installed
200 feet (61 m) of plastic riser pipe,
the pump may actually be down 204
feet (62 m). If the installation depth is
critical, check with the manufacturer
of the pipe to determine how to
compensate for pipe stretch.

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English (US)
6.7 Electrical and variable-frequency
drive information
Make sure that the voltage, phase number and
frequency of the power supply match those of
the motor. Motor voltage, phase number,
frequency and full-load current information can
be found on the nameplate attached to the
motor.
Motor electrical data can be found in section
10.6.1 Grundfos submersible motors, 60 Hz.
Direct-on-line starting is used due to the
extremely short run-up time of the motor
(maximum 0.1 second), and the low moment of
inertia of the pump and motor. Direct-on-line
starting current (locked rotor current) is between
4 and 6.5 times the full-load current.
If direct-on-line starting is not acceptable and
reduced starting current is required, use an
autotransformer or resistant starters for 5 to 30
hp motors, depending on the cable length. For
motors over 30 hp, use autotransformer starters.
WARNING
USA: All electrical work must be
performed by a qualified electrician
and installed in accordance with the
National Electrical Code, local codes
and regulations.
WARNING
Canada: All electrical work must be
performed by a qualified electrician
and installed in accordance with the
Canadian Electrical Code, local codes
and regulations.
WARNING
Provide acceptable grounding in
order to reduce the risk of electric
shock during operation of this pump.
If the means of connection to the box
connected to the power supply is
other than a grounded metal conduit,
ground the pump by connecting a
copper conductor, at least the size of
the circuit supplying the pump, to the
grounding screw provided within the
terminal box.
WARNING
If voltage variations are larger than
± 10 %, do not operate the pump.

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English (US)
6.7.1 Engine-driven generators
If the submersible pump is going to be operated
by an engine driven generator, we suggest that
you contact the manufacturer of the generator to
ensure the proper generator is selected and
used. See section 10.2 Guide for engine-driven
generators in submersible pump applications for
generator sizing guide.
If power is going to be supplied through
transformers, section 10.3 Transformer capacity
required for three-phase submersible motors
outlines the minimum KVA rating and capacity
required for satisfactory pump operation.
6.7.2 Control box or panel wiring
Single-phase motors
Connect single-phase motors as indicated in the
motor control box.
A typical single-phase wiring diagram using a
Grundfos control box is shown in fig. 11.
Fig. 11 Single-phase wiring diagram for Grundfos control boxes
Caution
CAUTION
Motor burnout protection via CUE,
CU331SP, or MP 204.
Use approved dry-run protection such
as with MP 204.
TM05 0037 2413
Control box
Fused
disconnect
switch
Red
Green
Yellow
Black Use dotted line for
115 V operation
Well seal
Pressure
switch

16
English (US)
Three-phase motors
Use three-phase motors with the proper size
and type of motor starter to ensure the motor is
protected against damage from low voltage,
phase failure, current imbalance and overload
current.
Use a properly sized starter with ambient-
compensated, class 10, extra quick-trip overload
relays or an MP204 to give the best possible
motor winding protection.
Each of the three motor legs must be
protected with overloads. The thermal
overloads must trip in less than 10 seconds at
locked rotor (starting) current. A three-phase
motor wiring diagram is shown in fig. 12.
Fig. 12 Three-phase wiring diagram for Grundfos motors and other motor manufacturers
Caution
CAUTION
Ensure that the pump is totally
submerged before you check the
direction of rotation. Severe damage
may be caused to the pump and
motor if they are run dry.
TM05 0038 2413
Power supply
Fused
disconnect
switch
Pressure
switch
Well
seal
Magnetic
starter
Green

17
English (US)
6.7.3 Variable-frequency drive operation
Grundfos motors
Three-phase Grundfos motors can be connected
to a variable frequency drive (VFD).
If a new temperature transmitter is required, a
Pt100/1000 sensor for fitting to the submersible
motor can be ordered from Grundfos.
During variable-frequency drive operation, we
recommend that you do not run the motor at a
frequency higher than the nominal frequency (50
or 60 Hz) and not lower than 30 Hz. In
connection with pump operation, it is important
never to reduce the frequency (and
consequently the speed) to such a low level that
the necessary flow of cooling liquid past the
motor is no longer ensured.
To avoid damage to the pump, make sure that
the motor stops when the pump flow falls below
0.1 x rated flow.
Depending on the type of variable frequency
drive, it may expose the motor to detrimental
voltage peaks.
The variable frequency drive must have some
kind of output sine-wave filter to limit voltage
peaks (Upeak) and to reduce dU/dt (or dV/dt)
which causes stress on the insulation of the
submersible motor. For sine-wave filter location
placement within the system, see fig. 13.
Note
If a Grundfos MS motor with
temperature transmitter is connected
to a variable frequency drive, a fuse
incorporated in the transmitter will
melt, and the transmitter will be
inactive. The transmitter cannot be
reactivated. This means that from that
point on, the motor will operate like a
motor without a temperature
transmitter.
Caution
CAUTION
We recommend that you protect your
motor from voltage peaks (Upeak)
and excess dU/dt (or dV/dt) by using
a sine-wave filter if one or more of the
following conditions are present:
• The motor nameplate voltage is
above 379 V.
• The variable frequency drive (VFD)
uses pulse width modulation
(PWM) and/or IGBT-BJT switches.
• The VFD voltage rise time is less
than 2 msec (NEMA MG 1-2011).
• The power cable length from the
VFD to the submersible motor
terminals is 0 to 1500 ft (0 to 457
m).
• The power quality is not stable.
• Keep the motor peak voltage
(Upeak) and dU/dt within the limits
listed in the table below.
For recommended best practice, use
a resistor-inductor-capacitor (RLC)
type sine-wave filter. An equivalent
type LC sine-wave filter is acceptable.
Consult the VFD manufacturer for
specific sine-wave filter
recommendation.

18
English (US)
Fig. 13 Location of the sine-wave filter in the system
For further details, contact your VFD supplier or
Grundfos.
Maximum peak voltage and dU/dt for Grundfos submersible motors
Motor series Maximum Upeak voltage Maximum dU/dt
MS 402 650 V phase-phase 2000 V/micro s.
MS 4000 850 V phase-phase 2000 V/micro s.
MS6 / MS 6000C 850 V phase-phase 2000 V/micro s.
MMS6 / MMS 6000 850 V phase-ground 500 V/micro s.
MMS 8000 850 V phase-ground 500 V/micro s.
MMS 10000 850 V phase-ground 500 V/micro s.
TM06 6056 0516
Sine-wave
filter Motor
VFD
379 V or
greater
incoming
power
Cable length from VFD to motor
0 to 1500 ft (0 to 457 m)

19
English (US)
6.7.4 High-voltage surge arresters
Use a high-voltage surge arrester to protect the
motor against lightning and switching surges.
Lightning voltage surges in power lines are
caused when lightning strikes somewhere in the
area.
Switching surges are caused by the opening and
closing of switches on the main high-voltage
distribution power lines.
Install the correct voltage-rated surge arrester
on the supply side of the control box. See fig. 14
and fig. 15. The arrester must be grounded in
accordance with the National Electrical Code
and local codes and regulations.
Fig. 14 Single-phase installation
Fig. 15 Three-phase installation
6.7.5 Control box or panel grounding
The ground wire must be a bare copper
conductor at least the same size as the
submersible drop cable wire size.
Run the ground wire as short a distance as
possible and fasten it securely to a true
grounding point.
TM05 0039 0611TM05 0040 0611
Single-phase
power supply
Ground
True
grounding
point
Lightning
arrester
T1 T2 T3
Three-phase power supply
Pump
control
panel
Lightning
arrester
True
grounding
point
Install
lightning
protectors
before fuses
or circuit
breaker
Ground
To MS motor
Note
The warranty on all three-phase
submersible motors becomes void in
these cases:
• The motor is operated with single-
phase power through a phase
converter.
• Three-leg ambient compensated,
extra quick-trip overload
protectors are not used.
• Three-phase current imbalance is
not checked and recorded. See
section 7. Startup.
• High-voltage surge arresters are
not installed.
WARNING
The control box or control panel must
be permanently grounded in
accordance with the National
Electrical Code and local codes or
regulations.

20
English (US)
True grounding points are considered to be one
of the following:
• a grounding rod driven into the water strata
• a steel well casing submerged into the water
lower than the pump installation depth
• steel outlet pipes without insulating
couplings.
If plastic outlet pipe and well casing are used or
if a grounding wire is required by local codes,
connect a properly sized, bare copper wire to a
stud on the motor and run to the control panel.
Fig. 16 Wiring and installation diagram
WARNING
Do not ground to a gas supply line.
Connect the grounding wire to the
ground point first and then to the
terminal in the control box or control
panel.
TM05 0041 0611
Power
supply
Electrical
dis-
connect
box
Control
box
House
supply
Conduit
connector
Submersible
drop cable
Pressure
gauge
Pressure
switch
Pressure
tank
Well
seal
Tape
Pump
Motor
Conduit*
* Conduit for proper support and
protection of the cable against
damage between the motor and
the point of supply connection.