The chassis of Danfoss Editron devices must always be connected to a suitable functional ground of the system. Failure of the device grounding, or missing grounding leads to lethal electrical shock hazard to personnel, and possible malfunctions and breakage of the devices, which are not covered under warranty. Never connect a high voltage source, rotate a motor or connect a battery or other power source to the devices without connecting the device chassis to a suitable ground.
In a vehicle or marine vessel, a suitable ground can be the metal chassis of the vehicle, or a similar, suitable solid metal structure with high current capacity and low impedance. In a stationary grid-connected setup, the device's chassis must be connected to the grid earth wire and/or building earth busbar. Note that the chassis should not be connected to the grid neutral point. Allowable grid connection type for Danfoss Editron systems is IT, with the device chassis always connected to the ground and/or PE wire.
The grounding cable(s) must be able to carry the maximum supply fault current which normally will be limited by the fuses or the Miniature Circuit Breaker (MCB). Install correctly rated fuses or MCB in the mains supply of the electrical device. The cross sectional area of the protective earth conductor must be at least equal to that of the incoming supply conductor.
Braided ground straps (shown in figure 1) have higher surface area compared to the cross-sectional area than regular round wires, and are thus more effective at providing protection against electromagnetic interference and radiated emissions from the devices.
Figure 1. Braided grounding strap.
Connect the ground terminal of each electric device individually to the site grounding bus bar (through the EMC/harmonic filter if installed). The grounding connections cannot loop from one electric device to another electric device, or to any other piece of equipment, or from any other piece of equipment. Make sure that all grounding surfaces are clean and remove paint from the contact areas.
Ground impedance must be compliant with national and local industrial safety regulations and electrical requirements. The condition of the grounding connections must be checked periodically.
The EC-C inverters should be connected to ground via the available installation/grounding bolt holes as illustrated in figure 2.
Figure 2. EC-C1200 inverter grounding points
The grounding points on the frame of the electric machine are for safety grounding of the motor chassis, see figure 3. Signal cables have their own grounding points in the low voltage signal connectors. Never connect any measurement signal (PT100, resolver, etc.) neutral wires to the ground pins of the connector, or on the motor chassis.
Figure 3. EM-PMI375 type motor grounding points
EM-PMI motors can also have additional grounding connection through the mounting flange of the unit, but the flange should never be used as the sole grounding connection. A separate grounding wire or strap should always be connected to the chassis grounding points.