KBAC series frequency converter installation and fault diagnosis guide

J8 (Relay Output Logic): The TB2 relay can be configured to indicate "operation" (R position) or "fault" (F position), and engineers can match the logic according to the input requirements of the upper computer PLC.

J9 (stop contact type): Factory set to "NO" (normally open). If the normally closed (NC) stop button is used on site, J9 must be moved to the "NC" position, otherwise the equipment cannot be started.

J10 (torque mode): Factory produced as "CT" (constant torque), suitable for machinery such as conveyor belts and extruders. If used for variable torque (HVAC) loads such as fans and pumps, setting it as "VT" can optimize energy efficiency and smooth operation.

J11 (I ² t overload curve selection): Factory set as "1" (frequency conversion dedicated motor). If ordinary non variable frequency motors or old motors are used on site, it is recommended to set them to "2" to relax the heating protection threshold for low-frequency operation and reduce false tripping.

Trimpot Calibration Guide

The 8 micro adjustment potentiometers on the panel (which need to be adjusted using insulation tools) are the key to the dynamic response of the tuning system.

MIN and MAX (minimum/maximum speed): MIN sets the lower limit frequency (factory 0%) for motor operation, and MAX sets the upper limit frequency (factory 100%). By adjusting, the maximum production capacity or minimum safe operating speed of the machine can be limited.

ACCEL and DECEL (acceleration/deceleration time): Factory default is 1.5 seconds. For large inertial loads, a short acceleration time can cause current limiting action (CL) and even overload reporting. Short deceleration time can cause high bus voltage (overvoltage fault). For high inertia loads, it is recommended to adjust the acceleration and deceleration time to at least 10 seconds and use the internal regeneration protection function to stop smoothly.

COMP (slip compensation): Factory set at 1.5V/Hz. If the motor's speed drops significantly under heavy load, the potentiometer can be adjusted clockwise to automatically increase the output voltage of the frequency converter when the load increases, maintaining a constant speed. Usually, excellent speed regulation can be achieved by combining with static self-tuning.

CL (current limiting): The factory setting is 160% of the rated current of the frequency converter. This is the core of protecting the motor! When adjusting, it is necessary to connect an AC clamp meter in series, adjust the speed to 30%, stall the motor, and quickly adjust the CL potentiometer to 160% of the rated current on the motor nameplate within 6 seconds. If the setting is too high, it will cause the motor to overheat and burn out, and if it is too low, it will frequently report overload.

BOOST (torque boost): It takes effect when J6 is set to "ADJ". Used to compensate for torque loss caused by motor stator resistance at low frequencies. Adjustment method: Run without load at around 4Hz, increase Boost clockwise until the current reaches the rated value on the motor nameplate.

JOG (Jog Speed): It needs to be used in conjunction with an optional Jog switch module to set the frequency of the movement.

LED diagnosis and common troubleshooting

The KBAC panel is equipped with two LED indicator lights, and understanding their flashing frequency is a "tool" for on-site troubleshooting.

PWR (power light): Always green when AC power is connected. Attention: The light on does not mean that the internal capacitor has been completely discharged. It must be completely powered off before maintenance.

ST (status light):

Slow flashing green: Normal operation.

Chang Lianghong: Overloaded (with a load of 120% -160%), it has not yet tripped, but it is necessary to immediately investigate the mechanical blockage.

Fast flashing red: The I ² t timer has timed out and tripped. The motor has been in an overloaded state for a long time. Disconnect the power supply and wait for it to cool down before troubleshooting.

Slow flashing red: Motor output phase to phase short circuit.

Fast flashing red/yellow: Input voltage undervoltage.

Slow flashing red/yellow: Input voltage overvoltage.

Always yellow: in stop mode.

Common fault scenarios and solutions:

Phenomenon: After connecting the power supply, the motor does not rotate and the status light remains on yellow.

Troubleshooting: Confirm if the Start/Stop switch is in the start position. Check if the J9 jumper matches the type of stop button (NO/NC). If remote start stop is used, check if the control line is disconnected.

Phenomenon: Overload is reported immediately upon startup (flashing red).

Troubleshooting: Check if the J2 jumper is set too large; Check if the CL potentiometer has been mistakenly adjusted to the extremely low position; Check if the mechanical load is stuck by foreign objects; Check if the acceleration time of ACCEL is too short, causing excessive starting current.

Phenomenon: After running for a period of time, it trips and can start again after a while.

Troubleshooting: This is a typical I ² t thermal protection action. Check if the ambient temperature on site exceeds 45 ℃; Check if the motor is operating at a current exceeding the nameplate; Check if the J11 jumper is configured correctly. It is recommended to set it to position "2" for ordinary motors.