Lenze i550 Error Codes and Reset Methods

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When a Lenze i550 stops with an error, the four-character code is more useful than the red LED alone. It tells you whether the drive detected an output short circuit, excessive DC-bus voltage, thermal overload, a missing supply phase, an invalid control assignment, or another condition that must be corrected before operation can resume.

The reset is usually simple. The diagnosis is the part that matters.

This guide explains the i550 code format, the most useful error codes for field troubleshooting, and the correct ways to reset the inverter without erasing its parameter set or repeatedly restarting into an active fault.

Scope: Which Lenze i550 Does This Guide Cover?

The quick-reference data below is based primarily on the Lenze i550 cabinet frequency inverter, 0.25 to 132 kW, Operating Instructions, May 2024. Lenze also offers i550 protec and i550 motec versions, and the i550 family is available with different control units, I/O configurations, networks, safety options, power ratings, and firmware versions.

The main diagnostic structure is similar across the family, but the available messages, parameter addresses, and reset behavior can vary. Always confirm the complete material number, firmware version, and exact product documentation before changing parameters.

The table in this article is a practical selection of common codes. It is not the complete i550 error list.

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Safety Before Working on a Lenze i550

Only qualified electrical personnel should open the cabinet or work on the inverter, motor, or connected machinery.

Isolate all power sources, apply the required lockout procedure, and secure the machine against unexpected movement. Lenze warns that hazardous voltage may remain at the inverter connections for up to 20 minutes after power-off. Observe the waiting time marked on the product, then verify that no voltage is present before touching the mains, DC-bus, braking, or motor terminals.

Do not rely on a dark display or stopped cooling fan as proof that the drive is de-energized. An externally supplied 24 V control circuit can also remain energized after the mains supply has been removed.

Disconnect the motor cable from the inverter before insulation-resistance testing. Testing through the drive can damage its electronics and produce misleading results.

How to Read a Lenze i550 Error Message

On the keypad, an active message includes three useful parts:

The error text, such as Warn. DC Bus UV
The response type: F for fault, T for trouble, or W for warning
The four-character hexadecimal error code, such as 3221 or FF02

Fault and trouble messages are displayed continuously and normally disable the inverter. Warnings appear briefly at intervals and may or may not inhibit operation, depending on the condition and configuration.

The active error can also be read in P150.00. For recurring or intermittent problems, use the diagnostics group and error history rather than clearing the message before recording it. Lenze’s i500 diagnostic guidance identifies P155 as the error logbook view on compatible firmware.

Record the complete message, not just the number. Also note what the machine was doing, the actual current, DC-bus voltage, heatsink temperature, run command state, and any events immediately before the trip.

Lenze i550 Error Code Quick Reference

Code	Official description	Type in the 2024 i550 cabinet instructions	First checks
2250	Continuous overcurrent inside the device	Error	Motor and cable short circuit, brake resistor wiring, star/delta connection, motor data
2320	Short circuit or earth leakage on motor side	Error	Motor cable, insulation, cable length and capacitance
2340	Short circuit inside the device	Error	Motor cable short circuit, output circuit, drive power stage
2350	I2t thermal overload	Error	Drive sizing, mechanical load, motor data, control tuning
2382	Device utilization Ixt too high	Error	Duty cycle, drive sizing, maximum current P324.00, high inertia
2383	Device utilization Ixt too high	Warning	Load trend and drive sizing
3120	Mains phase fault	Error	Input phases, fuses, contactor, terminals
3210	DC-bus overvoltage	Error	Deceleration, mains voltage, regenerative load, brake-energy management
3211	DC-bus overvoltage	Warning	Same checks as 3210, before the condition becomes a trip
3220	DC-bus undervoltage	Trouble	Mains voltage, fuses, P105.00, mains settings
3221	DC-bus undervoltage	Warning	Supply dip, loose connection, phase imbalance
3222	DC-bus voltage too low for switch-on	Warning	Mains supply, fuses, configured mains voltage
4210	Power unit overtemperature	Error	Cooling, fan, airflow, cabinet temperature, switching frequency
4281	Heatsink fan warning	Warning	Fan obstruction, contamination, fan condition
4310	Motor overtemperature	Error	Motor load, sizing, temperature sensor and X109 wiring
5112	24 V supply critical	Warning	External 24 V at X3/24E and mains voltage
5180	24 V supply overload	Warning	24 V output, digital outputs, earth fault, excessive load
6280	Trigger/functions connected incorrectly	Trouble	I/O function assignments and control source
7180	Motor overcurrent	Error	Motor load, drive sizing, threshold P353.01
9080	Keypad removed	Error	Reconnect keypad or select another control source
FF02	Brake resistor overload	Error	Braking duty, resistor sizing, brake-energy settings
FF06	Motor overspeed	Error	Maximum motor speed P322.00, threshold P350.01, load behavior
FF36	Brake resistor overload	Warning	Braking duty and resistor thermal load
FF37	Automatic start disabled	Error	Remove the active start command, then reset
FF85	Keypad full control active	Warning	Press CTRL to exit keypad control mode

Error 2250: Continuous Overcurrent

2250 means the inverter has detected continuous overcurrent inside the device. This does not automatically prove that the power unit is defective.

Lenze’s first checks are the motor and wiring, the brake resistor circuit, the motor star/delta connection, and the entered motor data. The code has a five-second blocking time in the 2024 operating instructions, so a valid reset will not be accepted until that time has elapsed and the cause is no longer active.

If 2250 appears immediately when the inverter is enabled, inspect for a phase-to-phase short, earth fault, wrong motor connection, or damaged output stage.

If it occurs during acceleration, compare the actual current with the motor and inverter ratings. Check P220.00 acceleration time, P323.00 rated motor current, P324.00 maximum current, motor nameplate data, and the mechanical breakaway load.

If the machine ran normally before the problem started, look for seized bearings, a jammed conveyor, a blocked pump, a damaged gearbox, or moisture in the motor cable before changing the drive parameters.

Errors 2320 and 2340: Short Circuit or Earth Leakage

2320 points to a short circuit or earth leakage on the motor side. Lenze specifically recommends checking the motor cable, its permitted length, and its capacitance. A long shielded cable can create higher charging current, particularly at a high switching frequency.

2340 is a short-circuit message associated with the device’s internal monitoring. The motor cable still needs to be checked before the inverter is condemned.

For either code:

Isolate the supply and observe the full discharge time.
Disconnect the motor cable from the inverter.
Inspect U, V, and W terminals, output contactors, cable glands, junction boxes, and motor leads.
Test the cable and motor separately using suitable procedures and instruments.
Confirm that no contactor is opening or closing in the motor circuit while the inverter is enabled.

Both codes have a five-second blocking time in the 2024 i550 cabinet instructions. Repeated resets without isolating the motor circuit can turn an external cable fault into a damaged power stage.

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Errors 2350, 2382, and 2383: Thermal and Drive Overload

These three messages are related, but they do not describe the same event.

2350 is an I2t thermal overload condition. Lenze advises checking drive sizing, excessive mechanical load, motor data, slip compensation, and oscillation damping. This is usually a duty-cycle or configuration problem rather than an instantaneous short circuit.

2382 means the calculated device utilization, or Ixt, is too high and has reached the error level. Check whether the inverter is correctly sized for the continuous current, overload demand, switching frequency, ambient temperature, and acceleration frequency. Lenze also points to maximum current P324.00; for high-inertia applications, the manual advises reducing the maximum overload current to 150 percent where appropriate.

2383 is the warning stage of excessive device utilization. Treat it as an early opportunity to review the load. Clearing the warning without changing the duty cycle only postpones 2382.

Error 3120: Mains Phase Fault

3120 means the inverter detected a mains phase problem. Check all incoming phases, fuses, circuit breakers, contactor poles, terminal torque, and voltage balance.

A normal voltage reading with the drive stopped does not rule out a weak fuse holder or contactor contact. Measure the supply under a controlled load condition if the installation and safety procedure permit it.

Also check whether the drive’s voltage class and mains configuration match the actual supply. Do not bypass phase-loss protection to keep a machine running.

Errors 3210 and 3211: DC-Bus Overvoltage

3210 is a DC-bus overvoltage error. 3211 is the warning for the same condition.

The most common field cause is regenerated energy during deceleration. When a high-inertia load drives the motor while the inverter is trying to slow it, energy returns to the DC bus and raises its voltage.

Start with these checks:

Increase deceleration time P221.00 and retest safely.
Check whether the load can overrun the motor, as with hoists, unwinders, centrifuges, large fans, and descending conveyors.
Measure the incoming mains voltage and look for high-line or switching disturbances.
Review brake-energy management and the installed brake resistor.
Confirm that the resistor value, power, duty cycle, wiring, and drive hardware are compatible.

The Lenze operating instructions refer to the brake-energy settings and activation of the integrated brake chopper when a suitable brake resistor is used. Do not change the braking mode or connect a resistor from resistance value alone. The exact inverter variant and resistor thermal rating matter.

Errors 3220, 3221, and 3222: DC-Bus Undervoltage

3220 is the undervoltage trouble response, 3221 is the warning level, and 3222 means the DC-bus voltage is too low for switch-on.

Check mains voltage, input fuses, phase balance, upstream contactors, and the configured mains setting. Read the DC-bus value in P105.00 and compare what happens at rest, during acceleration, and when other large loads start on the same supply.

If the code appears only when the machine accelerates, look for supply impedance, an undersized transformer, a loose terminal, or a contactor pole that drops voltage under load. If it appears immediately after a normal power-off, it may simply reflect the collapsing DC bus; use the event timing to separate a supply problem from a normal shutdown sequence.

Errors 4210, 4281, and 4310: Temperature Problems

4210 means the power unit is too hot. Check cabinet temperature, airflow direction, cooling clearances, clogged filters, fan operation, dust, and continuous load. The 2024 instructions identify P117.01 as the heatsink-temperature display and recommend reviewing switching frequency P305.00 when appropriate.

Do not reduce switching frequency blindly. Confirm the motor, acoustic, output-filter, cable-length, and application requirements first.

4281 warns of a heatsink fan problem. Clean the fan and ventilation openings and inspect whether the fan starts freely. Replace the fan if it is damaged or unreliable.

4310 is motor overtemperature. Check the actual motor load and cooling, then inspect the motor temperature sensor and its wiring at terminals X109/T1 and X109/T2. A broken sensor wire, incorrect sensor type, or loose terminal can produce the same code as a genuinely hot motor.

Errors 5112 and 5180: 24 V Control Supply

5112 indicates that the 24 V supply is critical. If an optional external supply is connected, check the voltage at X3/24E, its current capacity, common reference, and voltage during switching events. The mains supply should also be checked.

5180 means the 24 V supply is overloaded. Disconnect and test external loads methodically. Inspect digital outputs, relays or interface circuits powered from the drive, damaged field wiring, and shorts to earth.

A replacement control unit will not solve an external 24 V short. Find the branch that causes the voltage to collapse before reconnecting all loads.

Error 6280: Trigger or Function Assignment Is Incorrect

6280 is usually a configuration problem, not a power-electronics failure. The assigned triggers and control functions conflict or do not provide the signals required for the selected control method.

Review control selection and the assignments for inverter enable P400.01, run P400.02, quick stop P400.03, and error reset P400.04. With keypad or network control, Lenze notes that inverter enable and run can be assigned to Constant TRUE [1] where the application design permits it.

Do not combine forward/reverse start functions with forward/reverse run functions without checking the control concept. A PLC program change, downloaded parameter set, or replacement control unit can introduce this error even when the power wiring has not changed.

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Error 7180: Motor Overcurrent

7180 is the motor-overcurrent monitoring error. Check the motor load and drive sizing first. Lenze also points to the configured error threshold in P353.01.

This code should not be treated as identical to 2250. Code 2250 comes from continuous overcurrent monitoring inside the device and can indicate a more immediate electrical or power-stage condition. Code 7180 relates to the motor-current monitoring function and its configured threshold.

Before raising P353.01, confirm that the existing threshold is appropriate for the motor and machine. Increasing the limit can hide a genuine process overload.

Errors FF02 and FF36: Brake Resistor Overload

FF36 is the brake-resistor overload warning. FF02 is the error level.

Check resistor sizing, minimum permitted resistance, continuous and peak power, braking duty cycle, deceleration time, wiring, ventilation, and brake-energy settings. If the machine cycle has become faster or the moving mass has increased, a resistor that previously worked may now be thermally overloaded.

For FF02, the 2024 instructions state that the condition resets only when the calculated thermal load falls below the configured error threshold P707.09 by the specified 20-percent margin. Pressing reset repeatedly will not shorten that cooling period.

Errors FF06, FF37, FF85, and 9080

FF06 means motor overspeed. Check maximum motor speed P322.00, overspeed threshold P350.01, feedback or control stability, load overhauling, and whether the mechanical system can safely operate at the commanded speed.

FF37 means automatic start is disabled. Remove the active start command first, then reset the error. If the start input remains high, the drive is deliberately preventing an unexpected restart.

FF85 is a warning that keypad full-control mode is active. Press CTRL to leave that mode and return control to the intended source.

9080 appears when the keypad is removed while it is part of the active control arrangement. Reconnect the keypad or select another valid control source.

How to Reset a Lenze i550 Error

A reset is accepted only when the fault cause is no longer active and any blocking time has expired. After the error is acknowledged, a new enable or start command may be required.

Reset with the Keypad

Press the Stop key to reset the error. The motor remains stopped. Press Start only after the machine is safe and you are ready to resume operation.

Reset Through the Control Terminals

With the default terminal arrangement, there are two common methods:

Remove and reapply the run signal assigned through P400.02, normally digital input 1.
Apply the error-reset signal assigned through P400.04, normally digital input 2.

The assigned I/O can be changed, so verify the actual parameter set instead of assuming DI2 is always reset.

Reset with Lenze EASY Starter

Connect to the correct inverter, open the Diagnostics tab, confirm the active code and error history, correct the cause, and use the Reset command. EASY Starter is especially useful when the keypad text is abbreviated or the fault is intermittent.

Reset from a PLC or Fieldbus

The i550 can be acknowledged through the applicable network control word or mapped reset function. The exact bit depends on the selected network profile, process-data mapping, firmware, and control mode. Use the commissioning manual for the installed CANopen, EtherCAT, EtherNet/IP, PROFIBUS, PROFINET, POWERLINK, Modbus, or IO-Link interface.

Send a reset edge, not a permanently forced reset signal. Then issue a deliberate new enable or run command after confirming the drive is ready.

Reset by Cycling Power

Power cycling is not the preferred first response. Some internal faults may require mains switching, but most common operating errors should be diagnosed and reset through the normal acknowledgement path.

If power must be removed, follow the full 20-minute residual-voltage warning and verify the de-energized state before inspection. Repeatedly cycling mains power can hide intermittent evidence and adds unnecessary stress to upstream switching components.

Fault Reset Is Not the Same as Factory Reset

Do not use P700.01 to clear a normal error. That command loads the factory defaults into the inverter’s RAM and removes user parameter changes.

An error reset acknowledges a corrected fault. A factory reset changes the machine setup.

Before replacing a drive, control unit, or memory module, create and verify a parameter backup. Record firmware and communication settings as well as the motor data and application parameters.

Why the Lenze i550 Will Not Reset

If the Stop key, reset input, or EASY Starter command does not clear the code, check these points in order:

The cause is still present. A shorted cable, high DC bus, low supply, overtemperature, active start command, or overloaded brake resistor cannot be acknowledged away.
The blocking time is active. Codes such as 2250, 2320, 2340, 2350, 4310, and FF02 include a five-second blocking time in the 2024 instructions. 2382 uses three seconds, while 7180 and FF06 use one second.
The reset function is mapped elsewhere. Check P400.04, the active control source, and PLC process-data mapping.
A warning is still above its threshold. Some warnings clear only after voltage, temperature, current, or modeled thermal load returns to the permitted range.
A new start edge is missing. After reset, the drive may require the run or enable command to transition again.
The code requires a different recovery action. FF37, for example, requires the start command to be removed before reset.

A Practical Troubleshooting Sequence

Step 1: Preserve the Fault Evidence

Photograph the keypad and record the error text, type letter, four-character code, material number, firmware, motor nameplate, and operating stage. Read P150.00 and the error history before clearing anything.

Step 2: Identify When the Error Occurs

Operating stage	More likely areas to investigate
At power-up	Mains phase, undervoltage, 24 V supply, configuration, internal hardware
Immediately at enable	Output short, earth fault, motor connection, damaged power stage
During acceleration	Excess load, short ramp, incorrect motor data, drive sizing
At constant speed	Process overload, cooling, phase loss, intermittent insulation fault
During deceleration	Regeneration, DC-bus overvoltage, brake-resistor loading
After long operation	I2t/Ixt loading, cabinet temperature, fan or motor cooling

Step 3: Check the Mechanics

Inspect the driven machine before increasing current limits. Check bearings, couplings, gearboxes, belts, conveyors, fans, pumps, and process restrictions. Compare the current fault with recent maintenance or production changes.

Step 4: Check Supply and Motor Circuits

After safe isolation, inspect mains terminals, fuses, contactors, PE, motor terminals, cable glands, shields, output contactors, and the motor junction box. Test the motor and cable separately with the cable disconnected from the inverter.

Step 5: Verify the Parameter Set

Compare motor nameplate data with the entered values, then review control mode, acceleration P220.00, deceleration P221.00, switching frequency P305.00, rated motor current P323.00, maximum current P324.00, and any code-specific threshold.

Do not copy a parameter file into another i550 solely because the kW rating is the same. Hardware generation, voltage class, control unit, network, safety option, and firmware compatibility all matter.

Step 6: Reset and Run a Controlled Test

Remove the start command, correct the cause, wait for the blocking time or temperature condition, and reset once. Start at reduced risk and observe current, DC-bus voltage, temperature, and the exact point in the machine cycle.

If the same short-circuit, overcurrent, or internal error returns immediately, stop further reset attempts.

Frequently Asked Questions

How do I reset a Lenze i550 fault from the keypad?

Press the Stop key after the fault cause has been removed and the blocking time has expired. The motor remains stopped; press Start only when the machine is safe and a controlled restart is intended.

Why does my Lenze i550 error return immediately after reset?

The triggering condition is probably still active. Check the code-specific cause, such as a motor short, excessive DC-bus voltage, undervoltage, overheating, brake-resistor overload, or an active start command, rather than repeating the reset.

What is the difference between Lenze i550 codes 2250 and 7180?

2250 is continuous overcurrent detected inside the device, while 7180 is the motor-overcurrent monitoring error associated with motor load, drive sizing, and threshold P353.01. Both require load checks, but 2250 also calls for immediate inspection of motor wiring, connection, and the power circuit.

Why does error 3210 occur when the motor stops?

The motor is likely regenerating energy into the DC bus faster than the drive can manage it. Increase P221.00 deceleration time, check the mains voltage, then verify the brake resistor and brake-energy configuration for the exact i550 model.

How do I clear FF37 Automatic Start Disabled?

Remove the active start command first, then reset the error. The i550 uses FF37 to prevent the motor from starting unexpectedly while a run request is already present.

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When Should the i550 Be Replaced?

Replacement becomes reasonable when qualified testing has confirmed that the mains supply, motor cable, motor, brake resistor, 24 V loads, mechanical load, cooling, and parameter set are correct, but the fault persists under controlled conditions.

An error that remains with the motor circuit safely disconnected may increase suspicion of the power unit, but the service procedure for the exact i550 variant must still be followed. A control-assignment or communication error is not evidence that the power stage has failed.

Match a replacement by the complete Lenze material number, not only by output power. Confirm voltage class, rated current, overload duty, power-unit generation, control unit, I/O version, fieldbus, STO option, enclosure type, firmware, memory module, braking arrangement, and mechanical dimensions.

Kwoco can help identify a suitable Lenze i550 replacement when the original configuration is unclear or difficult to source. Useful information includes photos of every nameplate, the full error message, firmware, motor data, cabinet wiring, option modules, network type, and an EASY Starter parameter backup. This is usually enough to avoid an expensive mismatch while the machine is down.

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