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Nie, dziękuję Przekieruj mnie tamI have a LENZE E94AMHE0074 with DC bus undervoltage error. I have changed the drive still the problem persist.
• The DC-bus undervoltage alarm on an E94AMHE0074 axis module that re-appears even after the module has been replaced is almost never caused by the axis module itself.
• In a 9400 modular system the axis module does not create the DC link; it is supplied by the upstream Power Supply Module (PSM) through the common DC bus bars.
• Therefore the fault is almost certainly located in one of the following places (probability order):
System architecture
• E94AMHE0074 = 9400 HighLine Axis Module (AM).
• A separate E94APN… Power Supply Module rectifies the three-phase mains and feeds the ±DC bus (typically +DC, −DC, PE, +R, −R).
• All AMs are in parallel on copper bus bars; any disturbance anywhere on that bus will be “seen” by every AM.
Nominal voltages and trip thresholds
• 400 V AC mains → VDC_nom ≈ 400 V × √2 ≈ 565 V dc
• P9400 firmware trips for undervoltage at ~50-80 % of nominal; typical limit ≈ 430-460 V dc (parameter C00175 “LU adjustable”).
• Your observed 563 V trip means the DC is only dipping for milliseconds—just long enough to cross the threshold.
Root-cause categories
A. Input mains anomalies
– One phase open (blown NH fuse, defective contactor) → 1-phase rectification → VDC falls ≈ 30 %.
– Voltage sag under load (weak transformer, long cables, harmonic distortion).
B. PSM defects
– Age-fatigued electrolytic capacitors → poor energy storage.
– Rectifier bridge or pre-charge resistor contactor partially shorted/open.
C. Interconnection issues
– Loose M6/M8 screws on laminated bus bars: 10 mΩ at 40 A causes 0.4 V drop per point; under acceleration several hundred amperes flow and bus collapses.
– Incorrect PE routing causing high-frequency current loops → spurious trips.
D. Dynamic bus loading
– External braking chopper stuck ON or external brake resistor shorted.
– A different axis module with short-circuited IGBTs.
E. Parameter / firmware
– Mains voltage parameter C00173 set too low or “LU adjustable” set too high.
– Firmware < v6.0 had a rare bug that could mis-interpret the ADC reading after brown-out.
Measurement strategy (recommended sequence)
a. Safety: isolate, Lock-Out/Tag-Out, CAT III/1000 V meters, PPE gloves & visor.
b. With drives idle but energised:
• AC L1-L2, L2-L3, L3-L1 (expect ±5 % of nominal).
• DC at PSM +DC/−DC (should be √2 × VAC_rms).
c. Repeat while commanding the heaviest axis to accelerate. Record with a power-quality logger if available. Look for:
• ∆VAC > 10 % or any phase collapse.
• VDC dipping below limit, or ripple > 20 V pp.
d. If AC is stable but DC collapses → PSM or bus connection.
e. If DC at PSM is stable but DC at AM collapses → bus bar / cable / connector resistance.
f. If DC collapses only when braking → isolate brake resistor; if cured replace resistor or chopper.
• Lenze’s latest 9400 firmware (v12.0, 2023) adds oscilloscope capture of DC-bus events, easing root-cause capture.
• Modern power quality analysers (Fluke 1748, PQube 3e) store high-resolution half-cycle RMS data, letting you correlate sags with plant equipment (welders, presses).
• Condition-monitoring add-ons (Lenze X4 remote) can push undervoltage statistics to the cloud for predictive maintenance of plant transformers or PSM capacitors.
• Why one faulty axis can trip others: All axes share the same capacitors in the PSM; if one axis module has a shorted IGBT, it clamps the bus each PWM cycle, so other axes report LU (undervoltage) even though they are healthy.
• Analogy: think of the PSM as a hydraulic accumulator feeding many cylinders; a leak in any hose drops the common pressure and every cylinder “complains lack of pressure.”
• Parameter check cheat-sheet (400 V system):
– C00173 = 400 V
– C00175 (“LU adjustable”) ≤ 360 V (factory). Set back to default if in doubt.
• Work involves lethal voltages (> 600 V dc). Compliance with IEC 60204-1 (Machine safety—Electrical equipment) and local regulations is mandatory.
• Only certified personnel should defeat interlocks for measurement; all live probing must obey NFPA 70E / EN 50110 PPE levels.
• Dispose of failed PSM capacitors as hazardous electronic waste (RoHS, WEEE).
Potential challenges & mitigation
• Plant cannot be stopped long → use clip-on Rogowski coils and non-intrusive voltage probes for on-line measurement.
• No spare PSM → order capacitor kit (Lenze p/n E94APL…) and rebuild overnight.
• Very rarely the 9400 HighLine shows LU during boot if the 24 V logic supply is noisy or common-mode choked; make sure the 24 V PSU shares PE with the PSM.
• Firmware bugs before v05.40 can mis-calculate LU if mains parameter is set to 230 V instead of 400 V—verify firmware and parameter file loaded by Engineer.
• If the system is DC-bus-shared with regenerative supply modules (E94ARG…), undervoltage may instead be caused by their “sleep” mode being incorrectly parameterised.
• Examine harmonics and flicker standards EN 61000-3-11 compliance of your plant.
• Consider upgrading to Lenze i950 cabinet modules; they integrate active front-end that stabilises the DC bus against grid sags.
• Review Lenze application note AP_AE-9400-DCbus-share-2023 for advanced multi-axis diagnostics.
• Investigate installation of a small UPS for the 24 V logic rail and a ride-through capacitor module on the DC link for critical axes.
The axis module you replaced is almost certainly healthy; the undervoltage alarm is symptomatic of a supply-side weakness. Concentrate on:
1) verifying stable three-phase mains into the Power Supply Module,
2) confirming that the PSM actually delivers ≈ 565 V dc,
3) eliminating loose or resistive DC-bus connections, braking resistor shorts or another axis pulling the bus down, and
4) ensuring voltage-related parameters are set correctly.
Execute the outlined measurement plan—most cases are resolved by tightening bus bars or replacing an ageing PSM capacitor bank.
