Battery ground fault locator MGFL100

Overview
The Megger MGFL100 is a portable instrument designed to locate ground faults in battery systems and ungrounded AC/DC networks without taking systems offline. It uses a current clamp with a lightweight transmitter and receiver to identify the real fault circuit while discriminating reactive leakage due to stray capacitance.

Key features

• Locate battery system ground faults without shutdown
• Audible/visual alarm when the real fault circuit is identified
• Direct measurement of fault resistance and system stray capacitance
• Direct measurement of real fault current and leakage (reactive) current
• Adjustable current and voltage limits with password protection
• Operates from external AC supply or internal battery
• Locate faults up to 400 kΩ
• Works on AC and DC systems, including DC battery systems and protected IT networks
• Operates on systems up to 600 V (600 Vac with optional IT Filter for IT systems)
• Lightweight, portable transmitter and receiver for field tracing

Operation details
The MGFL100 distinguishes automatically between real fault current and reactive current caused by system stray capacitance so no complex tuning is required. Use the lightweight transmitter and receiver to trace faults; the sync cable separates real fault current from circuit leakage. The unit can be coupled directly to a line for tracing either offline or online when using the optional coupling IT Filter for IT networks.

Optional accessories
Use the optional IT Filter to enable locating ground faults on isolated-terra (IT) AC systems up to 600 Vac. Additional accessories include sync cable, current clamps and spare batteries.

Product documents (titles)

• MGFL100_ds_en.pdf (Data sheet)
• MGFL100_UG_en.pdf (User guide)
• IT-Filter_DS_EN.pdf (Data sheet for IT Filter)
• AC Tracing vs Pulse Application Note_v2A.pdf (Application note)
• Circuit Characterisation Application Note_v1.pdf (Application note)
• CT Magnetization_Application Note_v1.pdf (Application note)
• Stray Capacitance Applicatoin Note_v1.pdf (Application note)
• DC-ground-fault-locating-AC-coupling_CaseStudy1_EN.pdf (Case study)

Additional information
The receiver provides two displays: with the sync cable connected the top display shows current directed to the real fault and the lower display shows circuit leakage. Techniques for stabilising readings on noisy circuits are described, including placing the CT around both the circuit and its return or using two CTs to cancel noise.

Technical specifications

• Fault locating capability: up to 400 kΩ
• System compatibility: AC and DC systems, ungrounded systems, DC battery systems, protected IT networks
• Maximum operating voltage: up to 600 V (600 Vac with optional IT Filter for IT systems)
• Measured parameters: earth/ground fault resistance, system stray capacitance, real fault current, reactive leakage current
• Adjustable and password-protected current and voltage limits
• Power: external AC or internal battery
• Alarm function: audible/visual alarm when the real fault circuit is identified
• Portable design: lightweight transmitter and receiver for field use
• Noise handling: CT placement techniques and sync cable to separate real fault current from leakage
• Can locate high-impedance ground faults and faults on systems with high leakage current