Mobile Laboratory for Verification of Earthing Systems

he mobile laboratory is intended to check the efficiency of Earth systems.
The dispensing to the soil of the test current (1% minimum 50A) allows detection of the step and contact voltage and the measurement of the earth resistance of the cabin.
The mobile laboratory consists of all electronic equipment housed in the truck, inside the mobile unit Safety laced by cable and by the command module.
The generation of the current, the safety systems for the control of the test and the remote control with radio allow to perform all the measurements of step and contact for testing of ground systems.

The generator provides a sinusoidal AC voltage at 50Hz synchronous and in phase (or in opposition) with the power supply line. The electronic equipment is powered by a three-phase line to 380V 50Hz and capable of providing a power of 60kVA. The line voltage is rectified, filtered and used for the office of a bench of capacitors which supplies the IGBT inverter.
The latter is driven by a modulated PWM by the sinusoidal signal produced by a synchronized PLL with the line frequency.

The inverter output is filtered and sent to a transformer whose load is re-phased by a single phase 200 KVAR system that is specially designed and provides to maintain near the unity the power factor in case of inductive loads.

The front end of the alarm unit allows the radio communication between the generation system and the security of the mobile unit and allows the mutual intervention of the signaling safety system. The unit's front-end alarm signals the type of alarm and is connected to the unit via the mobile radio security through an antenna with a coaxial cable connected to the BNC connector on the panel.

The mobile security units protects operators and equipment from lightning, wrong actions or surges on auxiliary earth. The security unit is connected between the mobile lab and 3 conductor cable / line or AT MT.

The sending of generating commands (OPEN-DIRECT-REVERSE) is made with a radio communication system. The module is embedded in a container with protection degree IP56 on which there is a BNC connector for the antenna, a SRCN five-pin connector for power and charging, a power LED, a LED low-battery and three buttons with relative signal led to sending and receiving the generation status.

An automatic cycle can be activated locally by the switch on the front end of the control module or remotely through one of the control module. It enables a repeated sequence of commands OPEN-OPEN-DIRECT-REVERSE and allows the operator to make measurements at a higher per kilometer distance (maximum limit for remote radio control). Each command acts for a time interval of 40 seconds.