KEB F5 Elevator Driver Complete Guide

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).