Measuring functions:

• earth loop resistance measurement RE in multiply earthed earthing systems
• measurement of leakage and load currents from 0.3 mA to 35 A using the TRUE RMS measuring method

Features:

• precise due to TRUE RMS measuring method (AC, AC+DC)
• optical and acoustic alarm function in case of excessive earthing resistances
• large measuring clamp diameter of 38 mm
• memory of measured values/data logger for 116 measurements
• automatic calibration during start-up
• measuring category CAT III 300 V
• supplied in a hard-top case and with reference resistance loop

Functional principle:

• The measuring clamp has an excitation winding and a sensor winding.
• The excitation winding induces a current flow in the clamped earthing conductor via a constant AC voltage U (f = 3.333 kHz).
• The sensor winding measures the induced current flow.
• The BENNING CM E1 measures (calculates) the resistance of the entire earth loop Rs = U / I.

Advantage of earth resistance measurement without using rods:

• no need to disconnect the earthing conductor (often difficult because of corrosion)
• no need to install probes/auxiliary earth electrodes
• quick and easy measurement
• safe both for the testing personnel and the electrical installation (earthing is maintained during measurement)
• no failures of the electrical installation due to disconnection of the earth connection

Typical fields of application:

• electrical installations with parallel earth connections
  • overhead line networks with pole-type earth electrodes
  • lightning protection systems of buildings
  • street lighting, telecom applications, wind energy
  • …