Overvoltage Protection Triggered
Output voltage regulation circuit has detected voltage exceeding safe operating limits, typically 110-115% of nominal. Protection circuitry immediately shuts down output to prevent damage to connected equipment.
Error Code
AL68
Severity
Fault
Equipment
Power Supply
Manufacturer
Danfoss
Yellow OVP LED indicator flashing at 1Hz rate on status panel
Output voltage measures 28-32VDC on 24VDC rated supply before shutdown
Digital voltmeter display shows OV FAULT error code on front panel
Output relay contacts open with audible click during protection activation
Input current drops to near zero after initial surge during fault condition
Remote monitoring system receives overvoltage alarm signal via 4-20mA loop
Failed voltage feedback optocoupler TLP521 causing loss of regulation control
Defective output voltage sensing circuit with damaged precision resistor divider
Faulty PWM control IC UC3845 generating incorrect duty cycle commands
Open circuit in voltage feedback path from output to control circuit
Failed Zener diode reference voltage component in regulation circuit
Damaged secondary side rectifier diodes causing voltage multiplication effect
Implement LOTO safety protocol: isolate AC power and verify zero energy state
Measure output voltage with DMM: confirm overvoltage condition at 28-32VDC
Test feedback optocoupler TLP521: verify LED forward voltage 1.2V and phototransistor switching
Check voltage divider resistors R15/R16: measure 10kΩ and 1kΩ values within 1% tolerance
Replace PWM controller IC UC3845: verify pin voltages and oscillator frequency at 65kHz
Test output rectifier diodes D7/D8: check forward voltage drop 0.7V and reverse blocking
Calibrate output voltage using trimmer potentiometer: adjust to 24.0V ±0.5% under rated load
Safety First: Always isolate power and follow LOTO (Lockout/Tagout) procedures before working on electrical components. If unsure, contact a certified repair technician.
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