Contact Us Thunderstorm Electric Field Mill EFM550 Advance warning of overhead lightning threat Vaisala Thunderstorm Electric Field Mill EFM550 integrates with Vaisala local area, real-time lightning systems to monitor the development and dissipation of overhead lightning threats by measuring the local atmospheric electric field.?It also identifies when the threat has passed, providing valuable information to operations especially vulnerable to lightning.?EFM550 data can be displayed using optional Vaisala ALARM Automated Lightning Alert Risk Management Software to show current electric field measurements numerically and graphically. + Show more Key Benefits Advance warning of overhead lightning threat Provides high-resolution lightning threat data and minimizes false alarms. Exceptional reliability and low maintenance No preventative maintenance required during the first two years of operation. Flexible siting and easy installation Downloads Datasheet: EFM550 Datasheet (1.38 MB) All downloads Need support? Sign up for news Contact us