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MK-720 Corona Discharge Detector

MK-720 Corona Discharge Detector

Price $2,995.00
Corona Discharge Detector

The MK-720 is hand-held, battery-powered device designed to detect Electrical Arcing & Corona Discharge conditions --- without contact! Corona Discharge occurs when there is a problem with disconnectors, circuit breakers, insulators, etc leading to losses and potentially dangerous conditions. The MK-720 uses a proprietary algorithm to isolate the ultrasonic sound waves associated with Corona Discharge, separating it from the background noise performed, measured while the line is powered (hot). This algorithm significantly reduces the likelihood of false positive detection common with typical Ultrasonic Leak Detectors.

A large backlit LCD faces the user provide visual and audible indicators. A earphone is provided as part of the standard delivery helping the user to hear the audible tone alerting to the presence of Corona Discharge.

It features an over-sized ultrasonic receiver providing excellent range along with a focus with measurement in ±8° spot. It also features a laser pointer helping the user to visibly identify the target at all times.


  • Detects insulation deterioration on insulators, switches and circuit breakers!
  • Records measurement data (Component rate, Waveform, FFT data)
  • Precise measurement in ±8° spot
  • Easily transferable recorded data to PC via USB cable
  • Integrated Laser Pointer Identifies area of corona discharge
  • Generates audible sound from corona discharge and transmits through an earphone

Measuring Principle

Broadband ultrasound is emitted with corona discharge due to insulation deterioration at AC powered facilities. Since the intensity of the emitted ultrasound varies periodically with alternative voltage, double frequency components of power-supply appears prominently in frequency analysis after envelope detection of the received ultrasonic wave. MK-720 can detect corona discharge without effects of ambient noises by evaluating the intensity of double frequency components of the power-supply.

Measuring Principle

Measurement Display

Measurement display


Detecting frequency Central frequency 40kHz
Detecting directionality ±8°
Sensitivity MK-720 recognize discharge of 100pC to 300pC at 1 meter distance, as 20dB
Functions Display of discharge component rate
Display converted value in acoustic pressure
Alarm based on discharge component rate
Measuring point indication with laser pointer (Laser pointer light intensity Class 2 JIS C6802, Class 2 IEC 6825-1)
Data memory Discharge component rate and converted value in acoustic pressure Max. 500 data
Output Buzzer by setting max level
Signal output via 3.5mm mini jack
USB port for memory data output (USB mini B socket)
Power supply 4x AA alkaline battery (over 8 hours continuous use)
Dimensions W 174 X H 268 X D 98 mm
Weight Approx.400g (excluding batteries)
Temp Limits 32-104 °F / 0-40 °C, 10-85%RH (non condensing)
Standard configuration MK-720, 4x AA batteries, USB cable, Software (Win XP & 7) (CD) (MK-9804), Earphone, Strap, Instruction manual, Inspection sheet
Options Carrying case (MK-9703), Soft case (MK-9702), Reference oscillator (MP-161)


MK-720 Corona Discharge Detector - Data Sheet
MK-720 Corona Discharge Detector - Instruction Manual

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