KEB F5 Elevator Driver Complete Guide

From Installation to Troubleshooting: KEB COMBIVERT F5 Elevator Driver Practical Manual

In the elevator industry, the reliability and safety of drivers are directly related to passenger life and equipment safety. The KEB COMBIVERT F5 series elevator drive is designed specifically for traction elevators, supporting asynchronous motors and permanent magnet synchronous motors, with a power range covering 7.5hp to 250hp (230V/480V), and integrating a safety torque cutoff (STO) function that complies with ISO13849-1 and IEC61508 SIL3 levels. This article provides an immediately usable technical guide from the perspective of frontline maintenance, focusing on the hardware installation, encoder interface, core parameter configuration, typical fault handling, and safety function verification of F5 drives.

Safety and installation: an uncompromising foundation

Before starting any operation, it must be clear that the internal DC bus capacitor of the F5 driver can still maintain dangerous voltage after power failure. The manual clearly requires that "wait for at least 5 minutes after cutting off the input power" before conducting maintenance. In addition, due to the presence of ESD sensitive components inside, electrostatic protection measures must be taken before contacting the PCB.

Installation environment requirements:

Environmental temperature: -10 ℃~45 ℃. If it exceeds 40 ℃, remove the top protective label; Capacity reduction is required for altitudes exceeding 1000 meters (1% reduction per 100 meters).

Humidity below 95%, no condensation; Avoid corrosive gases, oil mist, and dust.

It must be installed vertically on a bare metal plate (galvanized steel or zinc plate) to ensure high-frequency grounding effect.

When multiple units are installed side by side, they can be tightly attached in the horizontal direction, but at least 20cm of heat dissipation space should be left above and below.

Grounding key:

The inverter casing must be directly connected to the equipotential grounding busbar of the control cabinet.

Use large-area metal contact (remove paint) and apply the manufacturer's recommended tightening torque.

An additional high-frequency grounding wire (with the same cross-section as the main power line or thick grounding braided tape) is used to connect the inverter to the metal substrate.

Prohibited items for main circuit wiring:

It is strictly prohibited to connect the input power to the U, V, and W output terminals, otherwise the internal IGBT will be instantly damaged.

It is prohibited to install power factor compensation capacitors or surge suppressors on the output side.

When the length of the motor cable exceeds 40 feet (approximately 12 meters), it is recommended to use dV/dt output reactors (KEB provides 15Z1F04 series).

The shielding layer of the shielded motor cable must be grounded at both the drive end and the motor end, but should not be used as a protective grounding conductor.

These basic rules are the prerequisite for the long-term stable operation of the equipment, and any negligence may lead to IGBT explosion or control board failure.

Deep analysis of control terminal and encoder interface

The control terminal block of F5 driver is divided into standard type (F5-A) and enhanced type with STO (F5-K, the fifth letter is K). The first challenge that engineers often encounter is the selection of SINK/Source logic and the configuration of encoder interfaces.

Digital input wiring:

SINK logic (NPN) using internal 24V power supply: COM (X2A. 8/9) is used as the common terminal, and current flows into the inverter when the input signal is closed.

Source logic (PNP) using internal 24V power supply: Use the P24 terminal as the common terminal, and when the input signal is closed, the current flows out.

When using an external 24V power supply, it is necessary to connect the external 0V to the inverter COM and connect the positive pole of the power supply to Vin (X2A.2 or X2A.21).

The drive enable input (I7) has a response of<1ms and must be independently controlled by the controller.

Analog input:

AN1+/AN1-: Default 0~10V speed command (direction determined by digital quantity), can also be configured as 0~20mA or 4~20mA through parameter LA50.

AN2+/AN2-: Default pre torque signal for load weighing devices (-10~+10V or 4~20mA), used in closed-loop simulation pre torque mode.

Encoder interface (X3A): This is the most critical link in F5 elevator applications. The manual provides a detailed list of various encoder interface boards:

Incremental TTL (stud terminal or SubD): 5V or 15/24V power supply. When there is no zero channel, N+needs to be connected to 5V and N - needs to be connected to COM, otherwise it will report "Error Encoder 1". The maximum frequency is 300kHz.

EnDat 2.1/2.2: 1Vpp sine/cosine differential signal, RS485 bidirectional serial data. Provide absolute position with a resolution of up to 24 bit single circle+12 bit multi circle. The maximum cable length is 110m (using KEB dedicated cables). Attention should be paid to the wiring of the shielding layer: the internal shielding should be connected to 0V (COM), and the external shielding should be connected to the ground.

Sin/Cos (1Vpp): Suitable for Heidenhain ERN 1387, etc., requiring high-resolution interpolation (LE05 multiplier factor is usually set to 8).

Hiperface: 7.5V power supply, 1Vpp incremental signal+RS485 serial data. The maximum cable length is 35m (calculated based on voltage drop).

SSi: Same 1Vpp increment+RS485 serial data, supports binary or Gray code formats.

BiSS/EnDat 2.2: Pure serial high-speed communication, with a maximum clock frequency of 4.16MHz and a maximum cable length of 50m.

UVW: Hall type commutation signal, used for square wave encoders.

For permanent magnet synchronous motors (PM), the absolute position of the encoder (LE06) must be learned before the first operation: static polarity recognition (SPI, LL05) or encoder pole position learning with motion (LL06) can be used. SPI does not need to disconnect the traction wheel, but requires the brake to be reliably closed; LL06 is suitable for balancing elevator cars or empty traction wheels.

Encoder simulation output (X3B): The X3A encoder signal can be divided and output to external systems (such as group control cabinets) through TTL RS422. The maximum frequency is 200kHz, and the load current is limited by the total capacity (500mA for 5V and 170mA for 24V).

Core parameter configuration and debugging process

The parameter structure of the F5 driver is extremely clear, divided into groups such as US (basic settings), LI (input), LM (motor data), LE (encoder), LN (mechanical data), LS (speed curve), LL (self-tuning), LC (control settings), LT (timer), LO (output), FB (fieldbus), etc. The following introduces key parameters in debugging order.

Basic Settings (US):

US02: British/metric units (ft/min or m/s).

US03: Motor type (induction with gears/without gears, permanent magnet with gears/without gears).

US04: Control type (digital speed selection, binary speed selection, absolute/bipolar analog speed, serial DIN66019 service 49/50, serial binary, etc.). Elevator control cabinets usually use binary or digital speed selection (0 or 1), and can also use CANopen (CiA417).

US05: Load configuration. After changing US02, US03, and US04, it is necessary to perform 'Write configuration to drive', and the new configuration will overwrite the previous parameters.

US06: Contract speed. The internal overspeed limit is automatically set to 110% of the contracted speed.

Motor data (LM):

Induction motors require input of power (LM01), speed (LM02, note that it must be the rated speed with slip, asynchronous speed), current (LM03), frequency (LM04), voltage (LM05), and power factor (LM06).

Permanent magnet motors require inputs: speed (LM02), current (LM03), frequency (LM04), voltage (LM05, usually the effective value of the back electromotive force at rated speed), and torque (LM07). Must verify motor pole number: LM04 × 120/LM02=even integer (pole number). If not met, adjust LM02 or LM04.

LM08: Motor overload protection (must be turned on), overload curve complies with UL508C, trip for 2 minutes at 150% current.

Motor parameter self-tuning: LL01=Start. The brake needs to be turned off, the external speed command set to zero, and the maintenance operation button (speed+direction+enable) pressed. The process takes about 2-5 minutes, and high-frequency noise will be emitted.

Mechanical Data (LN):

LN01: Traction wheel diameter (inches or mm).

LN02: Reduction ratio (X:1), for machines with gears, the correct ratio must be inputted; Gearless is 1.

LN03: Rope winding ratio (1:1, 2:1, 4:1, etc.).

LN05: Estimated reduction ratio (if unknown, recommended value can be calculated based on rated speed, contract speed, etc.).

These parameters directly affect the conversion from ft/min to rpm inside the drive, and incorrect settings can cause elevator speed deviation or overspeed faults.

Speed Curve (LS):

LS01: Leveling speed (default upper limit of 25fpm, can be unlocked up to 59fpm).

LS02: High speed (maximum contracted speed).

LS03: Maintenance speed (≤ 150fpm).

LS04: Calibration speed (high leveling speed).

LS05~07: Intermediate speeds 1-3 (for different floor distances).

LS15~17: Preset speed curve (soft, medium, hard). Automatically fill in acceleration, deceleration, and acceleration values after selection. LS20~45 can also be manually adjusted.

Note: For serial or analog speed control modes, the driver itself does not generate a speed curve, but the external curve can be limited to the driver's set value through the LS15=internal curve option.

Gain Adjustment (LC):

LC01: Control mode. Recommendation: Closed loop FOC (2) is used for induction motors; The closed-loop synthesis pre torque (5) is used for permanent magnet motors and does not require a weighing device.

LC02: Speed gain optimization. If inertia learning (LL10) has been completed, the scaling/integration gain can be adjusted from 0 to 25.

LC03/LC04: Proportional gain (acceleration/deceleration phase), typical initial value of 3000.

LC08/LC09: Integral gain (acceleration/deceleration phase), typical initial value of 250.

LC11/LC12: Integral offset gain (low-speed acceleration/deceleration range). For permanent magnet gearless traction machines, LC11 may require up to 2000~5000 to suppress starting slip.

LC30: Maximum torque (%), default 150%. Normal operation needs to be increased to 200-250%. Note: After synchronizing the drive and keyboard, LC30 will be reset to 150%!

LC34: Digital pre torque (used for fixed pre torque value in unloaded weighing devices).

Timer (LT):

LT01: Brake release delay (waiting time for the brake to open after enabling).

LT02: Control the holding off time (low gain time during brake closure).

LT03: Speed start delay (waiting for the brake to fully open before accelerating).

LT10: Brake release delay (delay before the brake closes during shutdown).

LT12: Current holding time (the time to maintain excitation current after the brake is closed).

LT13: Current ramp down time (the time when the current returns to zero).

Selection of Braking Resistors and Monitoring of Braking Transistors

The F5 driver integrates a brake chopper internally, but the resistor needs to be externally connected. The manual provides the minimum and typical braking resistance values for each chassis size. For example:

230V 15hp (G chassis): minimum 8.0 Ω, typical 13 Ω, maximum braking current 50A.

480V 100hp (U chassis): minimum 2.2 Ω, typical 4.3 Ω, maximum braking current 364A.

Key safety function: Brake transistor monitoring (K1/K2 terminals)

To prevent the brake transistor from short circuiting and causing the resistor to continue heating up and catching fire, the F5 driver (especially the version with STO) provides a monitoring relay output (K1/K2). It is a normally closed contact during normal operation. When the brake transistor fails (through), the monitoring circuit detects an abnormality and the K1/K2 contacts disconnect. The user must connect this contact to the external contactor coil to cut off the main power or DC circuit and disconnect the power supply to the resistor in case of a fault. Manual warning: Failure to implement this monitoring circuit may result in overheating of the resistor and cause a fire. The wiring diagram provides three options in section 2.2.16: monitoring through elevator controller, monitoring through DC contactor, and monitoring through line contactor.

Detailed explanation and testing of security functions

The F5-K model is equipped with an STO (Safe Torque Off) interface (X2B), which complies with ISO13849-1 PL e and SIL3. STO input has two independent channels (STO1+/STO1-, STO2+/STO2-), supporting OSSD pulse test signals from safety relays (maximum test interval of 10ms). When any channel or hardware enable (X2A. 16) is removed, the driver immediately blocks the IGBT pulse to achieve safe torque cut-off.

Key timing: Driver modulation possible condition=X2A.16 hardware enabled AND STO1 channel valid AND STO2 channel valid (relationship between the three). The status can be viewed in the DG01 diagnostic parameters (ST-EXT=8192, STO=4096).

Brake release confirmation: The digital input can be configured as "Brake release confirmation" (function 18). The driver will check if the brake switch is open after startup (LT01+LT03+2.5 seconds) and if it is closed after shutdown (LT10+LT12). If no signal is received after the timeout, trigger the 'brake switch fault'. LI20 can set reset behavior (universal reset, automatic reset 3 times, forced manual reset).

Unintended Movement Protection (UIM): enabled through LX21 and LX25. After normal operation, if the position of the motor changes beyond the set distance (default 200mm) in a stationary state, the driver triggers an "accidental movement" fault and needs to be manually reset by pressing F1+F4 at the same time. This feature complies with the latest requirements of EN81-20.

In depth investigation of typical fault codes

The F5 driver displays error messages through the LCD keyboard. The following are the common faults on site and their handling paths.

E.EEP（Error Encoder Interface）

Trigger condition: Absolute encoder serial communication interruption or loss of incremental signal.

Troubleshooting: Check the status of LE12 ("No Communication" indicates cable breakage, "Encoder Count Deviation" indicates A/B signal interference or pulse count mismatch). Try unplugging the encoder plug first. If it doesn't work, perform LE01 reset (press Enter after displaying LE01). After replacing the encoder, the driver will automatically detect the new encoder and clear errors, but must relearn the pole positions (LL05 or LL06).

E.OC（Overcurrent）

Trigger condition: The output current exceeds the peak rated value (see technical data sheet).

Reason: Motor cable grounding or phase to phase short circuit; Motor contactor contact erosion or delayed closure; IGBT short circuit (can be checked through diode testing).

Troubleshooting: Disconnect the motor wire and run the driver in open-loop V/Hz mode (LC01=0). If OC is not reported, the problem lies on the motor side; If OC is still reported, the inverter may be damaged.

E.OP（Overvoltage）

Trigger condition: The DC bus voltage exceeds 840V (480V level) or 400V (240V level).

Reason: The deceleration time is too short; The braking resistor is not connected or has a high resistance value; Brake transistor failure (measuring diode characteristics between PB and++). The input voltage of the braking resistor is 760VDC (480V level).

Solution: Increase deceleration time, check the wiring of the braking resistor, and test the braking transistor (see Section 12.1).

E. OL/E.OL2 (overload)

E. OL: Time dependent overload (see section 2.9), 150% trip per minute.

E. OL2: Low speed overload (when the current exceeds 1.4 times the rated value below 3Hz). Excessive current in permanent magnet motors is often caused by incorrect pole position of the encoder or incorrect motor data. Can check if LE06 deviates by more than 2000 counts after learning.

E.OS（Overspeed）

The internal speed limit is 110% of the contracted speed. Trigger reason: Mechanical data (LN) error leading to incorrect speed conversion; Insufficient maximum torque limit (LC30 too low); Encoder A/B is reversed (LE03); The pole position of the permanent magnet motor is incorrect. Need to confirm by comparing DG03 (instruction speed) and DG07 (actual speed).

Serial Command Speed Error / Speed Selection Error

In serial or analog speed control mode, if no valid speed command is received within LT03+20 seconds, it will be triggered. Not effective during maintenance operation. Solution: Check the communication or wiring of the controller to ensure that the speed command is given in a timely manner.

ESD/ETS Input Failure

When the input is configured as Emergency Deceleration (ESD) or Emergency Terminal Deceleration (ETS), if the input is not at a high level during startup, a fault is reported. Ensure that the safety circuit signal is normal.

Preventive maintenance and component replacement cycle

F5 drives are designed to have a long lifespan, but some components may age over time. Based on manual recommendations:

Typical failure phenomena of component standard replacement cycle

The cooling fan operates automatically with temperature control, but it is recommended to overheat (EOH), make noise, and not turn for 10 years

The main circuit electrolytic capacitor has a large voltage ripple and overvoltage/undervoltage false alarm after 10 years (normal environment)

Abnormal parameter storage and EEPROM failure of electrolytic capacitors on the control board after 10 years

Relay inspection results show that the contacts are stuck or unable to engage

Long term storage capacitor activation: If stored for more than 1 year after power failure, the capacitor needs to be aged before powering on. Specific steps are described in section 2.2.11: For drives stored for 1-2 years, power on for 1 hour without modulation; For storage for 2-3 years, an adjustable power supply should be used to slowly increase the voltage (held in stages according to the voltage level). If stored for more than 3 years, double the processing time for each additional year, or consider replacing the capacitor.

Insulation test: According to EN60204-1, a 500VDC megohmmeter is allowed, but all input terminals (L1, L2, L3), DC terminals (++, PA+, PB, -), and output terminals (U, V, W) must be short circuited together, and all 24V control signals must be grounded. Do not use AC voltage to test insulation, otherwise it may damage semiconductors and capacitors.

Advanced features and optimization suggestions

Inertial learning and FFTC: To achieve optimal ride comfort, LL10 inertia learning can be performed under balanced car conditions. The driver will automatically calculate the total inertia of the system (LC41) and activate feedforward torque control (FFTC). After learning, LC02 speed gain optimization can be used to adjust the response from soft to hard.

Pre torque adjustment:

When there is no weighing device, use closed-loop synthesis pre torque (LC01=5). The initial setting is to manually adjust LC10 (recommended 500~2000) and LC11 using closed-loop FOC (LC01=2), and then switch to synthesis mode after the rolling reduction. The drive will remember 90% of the load from the previous cycle as the pre torque for the next cycle.

When there is a weighing device, use closed-loop simulation pre torque (LC01=3) to calibrate the pre torque at no-load and full load through LA15 (gain) and LA17 (offset).

Maintenance operation and unexpected movement: During maintenance operation, the maintenance speed input (function 32) should be kept high, otherwise the driver may falsely report "enable premature removal". Unexpected movement detection is automatically disabled during maintenance operations.

Firmware version compatibility: v3.34 keyboard and control card v4.3 and above are compatible, and can upload parameters of v3.21 and above versions. The old version keyboard cannot download v3.34 configuration.