Submersible Pump Not Starting: Causes And Troubleshooting

Why Is A Submersible Pump Not Starting?

Submersible Pump Not Starting Problems Usually Result From A Missing Power Supply, Tripped Protection Device, Faulty Pressure Switch, Damaged Control Box, Low Voltage, Open Cable, Failed Capacitor, Motor Winding Fault, Or Locked Pump.

The Safest Troubleshooting Sequence Starts At The Power Supply And Moves Toward The Pump.

First, Check Breakers, fuses, disconnects, control signals, And Fault codes. Then, Measure Voltage And Current At The Control panel.

If The Motor Still Does Not Start, Test The Cable And Motor windings After Completely Disconnecting Them From The Drive Or Control equipment.

Never Pull The Pump Before Testing Accessible electrical And Control components. Many Starting Problems Develop Above Ground.

Important Electrical Safety Warning

Submersible Pump Systems Use Potentially Lethal voltage.

Only Qualified Personnel Should Open Control panels, test energized circuits, replace capacitors, Or Perform Motor insulation tests.

Before Starting Work:

• Disconnect The Main Power
• Apply Lockout And Tagout Procedures
• Verify Zero Voltage
• Follow Local Electrical Codes
• Use Correctly Rated Test Equipment
• Wear Suitable Personal Protective Equipment
• Discharge Capacitors According To Manufacturer Instructions
• Prevent Automatic Restart
• Isolate Generator Or Solar Power Sources

Never Discharge A Capacitor By Shorting Its Terminals With A Screwdriver.

Never Perform An Insulation-Resistance Test Through A Variable Frequency Drive, Electronic Controller, Or Sensitive Protection relay.

Identify The Exact Starting Symptom

Different Symptoms Point Toward Different causes.

Check The Power Supply First

Tripped Circuit Breaker

A Circuit Breaker May Trip Because Of:

• Short Circuit
• Ground Fault
• Motor Overload
• Locked Rotor
• Damaged Cable
• Water Inside A Connection
• Incorrect Breaker Size
• Loose Terminal
• Supply Surge

Resetting A Breaker Once May Help Identify A Temporary event.

However, Repeatedly Resetting A Breaker Without Finding The Cause Can Damage The Motor, cable, And Control panel.

If The Breaker Trips Again, Disconnect The Equipment And Perform Electrical tests.

Blown Fuse

A Blown Fuse Interrupts Power To The Motor Or Control circuit.

Three-Phase Systems Can Lose Only One Fuse. The Remaining Phases May still Remain energized.

Never Assume A Circuit Is Safe Because The Motor Does Not run.

Replace A Fuse Only With The Correct Type, voltage rating, current rating, And Interrupting capacity.

Open Disconnect Switch

Check The Main Disconnect, local isolator, emergency-stop circuit, And Remote control switch.

A Service technician May Have Left A Disconnect Open After Maintenance.

Corroded Or Burned disconnect contacts Can Also Prevent Full voltage From Reaching The motor.

Utility Power Failure

Measure The Actual supply voltage.

A Control Panel Light May Operate Even When The Motor supply Is Missing Or Incomplete.

For Three-Phase Systems, Measure All Three Line-to-line voltages.

Undersized Generator

A Generator May Produce Acceptable voltage Before The Pump starts But Collapse Under Starting load.

Submersible Motors Can Require Significant starting current.

Generator Selection Must Consider:

• Motor Power
• Starting Method
• Locked-Rotor Current
• Other Connected Loads
• Cable Voltage Drop
• Power Factor
• Generator Voltage Regulation

A Generator That Is Too Small May Cause Humming, contactor chatter, slow acceleration, Or overload trips.

Check The Pressure Switch

The Pressure Switch Starts The Pump When System pressure Falls To The cut-in value.

If System pressure Remains Above Cut-In, The Pump Should Not start. This Is Normal operation.

A Pump May Fail To Start Because The Pressure Switch Has:

• Burned Contacts
• Corroded Contacts
• Loose Wiring
• A Broken Spring
• A Blocked Pressure Port
• Incorrect Settings
• A Damaged Diaphragm
• No Pressure Signal
• A Manual Low-Pressure Lockout

Check The Pressure Gauge And Compare It With The Switch operation.

Do Not Touch Energized Pressure-switch terminals.

The Submersible Pump Pressure Switch: Complete Guide Explains Cut-In, Cut-Out, Differential Pressure, And Common Switch Problems.

Check Low-Pressure Cutoff Protection

Some Pressure Switches Include A Low-pressure cutoff.

If System Pressure Falls Below The Protection threshold, The Switch disconnects The Pump. A Manual reset May Be Required.

This Function Helps Protect Against:

• Broken Pipes
• Dry Wells
• Loss Of Prime In Surface Systems
• Major Leakage
• Insufficient Pump Output

Do Not Hold A Manual-reset lever Continuously To Force Operation.

If Pressure Cannot recover, Find The Hydraulic Or Electrical cause Before Restarting.

Check The Pressure Tank

A Pressure Tank Does Not Directly start The Motor. However, It Influences Pressure-switch operation.

Incorrect precharge, a ruptured bladder, Or A Waterlogged tank Can Cause Rapid Cycling.

Frequent Cycling May Overheat The Motor And Activate Thermal protection.

Test The Tank Only After Disconnecting Power And Draining Water pressure To zero.

Use The Submersible Pump Pressure Tank: Complete Sizing Guide For Correct Testing And Precharge Information.

Check The Control Box

A Three-Wire Single-Phase Submersible Motor Usually Requires An External Control box.

The Control Box May Contain:

• Start Capacitor
• Run Capacitor
• Starting Relay
• Overload Protector
• Contactor
• Terminal Block
• Surge Protection

A Failed Capacitor Can Prevent The Motor From Developing Enough starting torque.

A Damaged Start relay May Leave The Start winding disconnected Or connected For Too long.

Burned Terminals And Loose connections Can Create Voltage Drop And heat.

Use A Control Box That Matches The Motor’s voltage, power, phase, And Manufacturer requirements.

The Electric Control Box For Submersible Pump Guide Explains Common Components And Connections.

Two-Wire Versus Three-Wire Motors

A Two-Wire Single-Phase Motor Usually Contains Its Starting components Inside The motor. The Installation Normally Uses Two Power conductors Plus Ground.

A Three-Wire Single-Phase Motor Usually Uses An External Control box. It Normally Has Separate Common, run, And start conductors Plus Ground.

Conductor colors Are Not Universal Across Every Manufacturer Or region.

Always Follow The Motor wiring diagram.

Connecting A Two-Wire Motor To An Incorrect External Box Or Miswiring A Three-Wire Motor Can Prevent startup And Damage The windings.

Check Motor Overload Protection

Motor Protection Can Stop The Pump Because Of:

• Excessive Current
• Locked Rotor
• Phase Loss
• Voltage Imbalance
• Low Voltage
• High Voltage
• Motor Overheating
• Excessive Starting Time
• Frequent Cycling
• Incorrect Overload Setting

Some Overloads Reset Automatically After Cooling. Others Require A Manual reset.

Do Not Increase The Overload setting To Keep A Faulty Pump running.

The Setting Must Match The Motor nameplate And Protection manufacturer’s instructions.

Grundfos Provides A Specific Procedure For Setting Submersible Pump Motor Protection And Warns Against Exceeding The Motor’s stamped maximum current.

The Submersible Pump Overload Protection: Complete Guide Covers Overcurrent, locked rotor, And Thermal protection.

Low Voltage And Excessive Voltage Drop

Low Voltage Reduces Starting torque And Increases Motor current.

The Motor May hum Without Reaching Full speed. The Overload Then trips.

Voltage Drop Can Result From:

• Undersized Cable
• Excessive Cable Length
• Loose Connections
• Damaged Splices
• Corroded Terminals
• Weak Transformer
• Small Generator
• Long Extension Wiring
• Overloaded Supply Circuit

Measure Voltage During The Starting attempt. An Unloaded voltage reading May Look Normal Even When The Supply collapses Under load.

Use The Submersible Pump Cable: Complete Selection Guide To Select Cable From Motor current, voltage, length, And Permitted voltage drop.

High Voltage

High Voltage Can Increase Magnetic stress, heat, And Starting shock.

The Protection relay Or Drive May Block Startup When Supply voltage Exceeds Its programmed limit.

Measure Actual voltage And Compare It With Motor And Controller tolerances.

Do Not Assume That Higher Voltage Helps A Motor start.

Voltage Imbalance And Phase Loss

A Three-Phase Motor Requires Three Balanced supply phases.

Phase Loss Can Occur Because Of:

• Blown Fuse
• Open Contactor Pole
• Loose Cable
• Damaged Terminal
• Broken Conductor
• Utility Fault
• Transformer Problem

A Motor May Fail To Start Or May Draw Very High current On The Remaining phases.

Voltage imbalance Also Produces Large current imbalance And motor heating.

The Submersible Pump Voltage Protection: Complete Guide Explains Phase loss, voltage imbalance, And Protection settings.

Contactor Problems

A Contactor Uses A Control signal To Connect Motor power.

Common Contactor faults Include:

• Burned Main Contacts
• Failed Coil
• Low Coil Voltage
• Loose Control Wiring
• Mechanical Jamming
• Contaminated Contacts
• Incorrect Coil Rating
• Rapid Chattering

A Contactor That Closes Does Not Guarantee That All Motor phases Receive Power.

Measure Voltage On Both The Line And Load sides.

Replace A Damaged Contactor With A Correctly rated device.

Faulty Float Switch Or Level Sensor

Water-level controls Can Prevent Startup When They Detect A Low-water condition.

A Faulty float, probe, electrode relay, Or level transmitter May Report An Incorrect level.

Inspect:

• Sensor Position
• Cable Condition
• Terminal Connections
• Deposit Buildup
• Float Movement
• Probe Conductivity
• Controller Input Status
• Stop And Restart Levels

Never Bypass Low-water protection For Normal operation.

A Temporary diagnostic bypass Should Follow Manufacturer instructions And Remain Under Qualified supervision.

Dry-Run Controller Lockout

A Dry-run relay May Detect Low current, low power, low flow, Or Low water level.

The Controller Can Then Apply A Recovery delay Before Restarting.

The Pump May Appear Faulty During This delay.

Check The Controller display, alarm code, trip history, And Remaining recovery time.

Repeated Dry-run alarms Usually Indicate Low well yield, excessive pump capacity, Or Incorrect threshold settings.

Variable Frequency Drive Does Not Start

A VFD May Block Motor startup Because Of:

• Missing Run Command
• Open Interlock
• Low-Level Signal
• Pressure Sensor Fault
• Underload Alarm
• Overcurrent Alarm
• Overvoltage
• Undervoltage
• Phase Loss
• Ground Fault
• Motor Temperature Alarm
• Incorrect Motor Data
• Communication Failure
• Emergency Stop
• Minimum Off-Time

Check The Drive’s Fault code Before Resetting It.

Record The Code And Operating data. Repeated resets Can Erase Useful diagnostic information Or Expose The Motor To More damage.

Review The Variable Frequency Drive For Submersible Pump: Complete Guide For Motor Data And Protection settings.

Soft Starter Problems

A Soft Starter Controls Voltage Or Current During acceleration.

Incorrect ramp time, current limit, bypass contactor operation, Or motor data Can Prevent Full startup.

A Current Limit Set Too Low May Not Provide Enough starting torque.

A Ramp Time Set Too Long Can Keep The Motor In A High-slip condition And Trigger Protection.

The Submersible Pump Soft Starter: Complete Guide Explains Bypass contactors, ramp settings, And Starting protection.

Open Or Damaged Pump Cable

A Cable Fault Can Interrupt One Or More Motor conductors.

Common Causes Include:

• Damaged Insulation
• Poor Splice
• Corroded Connection
• Cable Stretch
• Abrasion Against The Well Casing
• Incorrect Cable Support
• Water Entry
• Lightning Damage
• Rodent Or Mechanical Damage Above Ground

A Continuity test Can Identify An Open conductor.

An Insulation-resistance test Can Detect Leakage Between A Conductor And ground.

Disconnect The Motor cable From Electronic equipment Before Testing.

Ground Fault

A Ground Fault Occurs When Electrical current Escapes Through Damaged insulation To Ground Or Water.

Possible locations Include:

• Motor Windings
• Drop Cable
• Cable Splice
• Wellhead Connection
• Control Panel
• Junction Box

A Ground Fault Can Trip A Breaker, fuse, drive, Or Motor protector Immediately.

Do Not Re-Energize A Confirmed Ground fault.

Open Motor Winding

A Broken Winding connection Prevents Current From Flowing Through The Required circuit.

A Qualified technician Can Measure Resistance Between Motor leads.

Compare Results With The Motor Manufacturer’s resistance data.

Include Cable resistance When Testing From The surface.

An Infinite Or Abnormally high resistance Can Indicate An Open cable, splice, Or Winding.

Shorted Motor Winding

A Turn-to-turn Or Phase-to-phase short Can Create Excessive current.

Standard resistance measurements May Not Detect Every Turn short Because The Resistance difference Can Be small.

Current imbalance, insulation tests, surge testing, Or Professional Motor evaluation May Be Required.

Incorrect Winding Resistance

Resistance Values Change With Conductor length, cable size, And temperature.

Do Not Compare Surface measurements Directly With Bare Motor values Without Accounting For Drop-cable resistance.

Three-Phase winding resistances Should Remain Closely balanced.

A Significant difference Indicates A Connection, cable, Or Motor problem.

Locked Pump Or Rotor

Sand, scale, corrosion, debris, bearing failure, Or Mechanical deformation Can Prevent The Pump From rotating.

The Motor Then Draws Locked-rotor current Without accelerating.

Protection Should Stop The Motor quickly.

Common Mechanical Causes Include:

• Seized Radial Bearing
• Damaged Thrust Bearing
• Jammed Impeller
• Bent Shaft
• Sand Accumulation
• Corroded Stages
• Damaged Coupling
• Frozen Hydraulic Parts
• Foreign Material

Do Not Repeatedly Apply Power To A Locked pump.

Long-Term Storage And Seizure

A Pump That Remains Unused For A Long period Can Develop Deposits Or Corrosion.

The Motor May receive Power But Fail To turn.

Follow The Pump Manufacturer’s procedure For Testing Shaft rotation.

Some Deep Well Pump assemblies Cannot Be Safely rotated Or accessed While Installed.

Pump Starts But No Water Arrives

A Motor That Runs Without Delivering Water Has A Different problem From A Motor That Does Not Start.

Possible Causes Include:

• Low Water Level
• Dry Well
• Closed Valve
• Broken Riser Pipe
• Failed Check Valve
• Damaged Coupling
• Worn Impellers
• Incorrect Rotation
• Blocked Inlet
• Air Or Gas
• Insufficient Pump Head

Check Motor current, flow, discharge pressure, And Dynamic water level.

Complete Troubleshooting Sequence

Step 1: Record The Symptoms

Record:

• Pressure Gauge Reading
• Controller Status
• Fault Code
• Breaker Position
• Motor Sound
• Starting Current
• Time Before Trip
• Water Flow
• Recent Maintenance
• Recent Power Events

Do Not Reset The System Before Recording fault information.

Step 2: Verify The Start Demand

Confirm That The Pressure switch, level control, timer, PLC, Or Remote command Requests Pump operation.

Check Every Interlock In The control circuit.

Step 3: Check Supply Voltage

Measure Line voltage At The Panel.

For Three-Phase systems, measure All Three line-to-line values.

Step 4: Check Voltage At The Motor Output

Measure Voltage At The Contactor, control box, starter, Or Drive output As Appropriate.

Electronic Drive outputs Require Suitable meters And Procedures.

Step 5: Measure Starting Current

Measure Current On Every Motor conductor During The Start attempt.

The Current pattern Helps Separate An Open circuit, phase loss, locked rotor, And No-start command.

Step 6: Inspect Accessible Components

Inspect Fuses, contactors, capacitors, relays, terminals, pressure switches, And Sensor wiring.

Look For Heat damage, corrosion, loose connections, water entry, And Insect contamination.

Step 7: Isolate The Motor And Cable

Disconnect The Motor cable From The Controller.

Label Every conductor Before Disconnection.

Follow The Motor wiring diagram.

Step 8: Measure Winding Resistance

Measure Resistance Between The Required lead combinations.

Compare The Results With Manufacturer data After Accounting For Cable resistance And temperature.

Step 9: Test Insulation Resistance

Test Each Motor conductor To ground Using A Manufacturer-approved voltage And Procedure.

Do Not Test Through Control electronics.

A Low insulation-resistance result Can Indicate Cable, splice, Or Motor damage.

Step 10: Separate Cable And Motor When Necessary

If Surface tests Show A Fault, technicians May Need To Pull The Pump.

Testing The Motor And Cable separately Identifies The Failed component.

Step 11: Inspect The Mechanical Assembly

Check The Shaft, coupling, impellers, diffusers, bearings, And Inlet screen.

Look For Sand, corrosion, deposits, And Mechanical seizure.

When Should The Pump Be Pulled?

Consider Pulling The Pump When:

• Electrical Tests Identify A Downhole Fault
• Motor Insulation Resistance Is Unacceptable
• A Conductor Remains Open
• The Pump Is Mechanically Locked
• The Motor Runs But Produces No Water
• A Riser Pipe Leak Is Suspected
• The Coupling Has Failed
• Hydraulic Components Show Severe Wear
• All Above-Ground Controls Test Correctly

Do Not Pull A Deep Well Pump Before Confirming The Wellhead equipment, controls, and Power supply.

How To Prevent Future Starting Problems

Install Complete Motor Protection

Use Protection For:

• Overload
• Locked Rotor
• Phase Loss
• Voltage Imbalance
• High Voltage
• Low Voltage
• Dry Running
• Excessive Starts
• Overtemperature
• Ground Fault

Use The Correct Cable

Select Cable From Motor current, voltage, depth, And Starting method.

Support The Cable Along The Riser pipe And Protect It From Sharp edges.

Control Starting Frequency

Use A Correctly sized pressure tank, anti-cycling delay, Or variable-speed control.

Frequent starting Increases Motor And Contactor heat.

Maintain Dry-Run Protection

Test Level probes, float switches, underload relays, And recovery timers.

Do Not Disable A Repeated alarm Without Finding Its cause.

Inspect The Control Panel

Check Terminals, contactors, ventilation, capacitors, surge protection, And Enclosure seals.

Keep Water, insects, dust, And Corrosive vapors Out Of The panel.

Record Baseline Data

After Installation, Record:

• Supply Voltage
• Running Current
• Winding Resistance
• Insulation Resistance
• Flow Rate
• Pressure
• Dynamic Water Level
• Start Time
• Controller Settings

Baseline Data Makes Future Troubleshooting Faster.

The Franklin Electric AIM Resources Provide Application, Installation, And Maintenance Information For Submersible Motors.

Frequently Asked Questions

Why Does My Submersible Pump Make No Sound?

The Motor May Not Receive Power.

Check The Breaker, fuse, disconnect, pressure switch, contactor, controller, cable, And Motor windings.

Why Does The Motor Hum But Not Start?

Common Causes Include Low voltage, a failed capacitor, locked pump, incorrect wiring, Or Insufficient generator capacity.

Disconnect Power Quickly To Prevent winding damage.

Why Does The Breaker Trip Immediately?

A Short circuit, ground fault, locked rotor, damaged cable, Or Incorrectly sized breaker May Be Present.

Do Not Repeatedly Reset It.

Why Does The Pump Start After Cooling?

The Motor Or Overload protector May Be Overheating.

Check Current, voltage, cycling frequency, water flow, motor cooling, And Mechanical load.

Can A Bad Pressure Switch Stop The Pump From Starting?

Yes. Burned contacts, blocked sensing ports, loose wires, Or Incorrect settings Can Prevent The Start signal.

Can Low Voltage Stop A Submersible Pump?

Yes. Low Voltage Reduces starting torque And Can Cause High current, humming, or Overload trips.

Can A Failed Capacitor Damage The Motor?

Yes. A Failed Start capacitor Can Prevent acceleration.

A Failed Run capacitor Can Increase Current, heat, And Reduce performance.

Can I Test The Motor Without Pulling The Pump?

Yes. Technicians Can Measure winding resistance And insulation resistance From The surface.

However, Surface measurements Include The Drop cable And splice.

Should I Reset A VFD Fault?

Record The Fault First.

Reset It Only After Confirming That Restarting Will Not Damage The Pump, motor, Or System.

Why Does The Pump Run Manually But Not Automatically?

The Motor Power Circuit Works, But The Automatic control circuit May Have A Fault.

Check The Pressure switch, level sensor, timer, PLC command, relay, And Interlocks.

Conclusion

Submersible Pump Not Starting Problems Can Develop In The Power supply, pressure controls, control box, cable, motor, Or Mechanical pump assembly.

Start With The Breaker, fuses, disconnects, fault codes, pressure switch, And Controller inputs.

Then, Measure supply voltage, starting current, winding resistance, And Insulation resistance.

Do Not Repeatedly Reset A Tripping breaker Or overload. These Devices Usually Indicate A Real Electrical Or Mechanical problem.

Liyuan Pump Can Evaluate Motor voltage, power, phase, cable length, starting method, control requirements, well depth, And Pump duty To Develop A Reliable Deep Well Pumping System.