practical case. Feature of the equipment OSN 6800/8800

In case of this emergency operation the equipment continues to work. And instead of operation "-" - "+" we get a job "-" - the earth. That is on parasitic ways there passes the main part of a working current. Thus such parasitic jumpers are also between a floor and a cabinet, and also between a cabinet and a cable tray through connective bolts.

During the exploitation of OSN8800 I faced to strange situation: due to existing deadshort between pin “+” and “PE” in PDU a return current flows through a main way and a secondary way. The secondary one consist of PE-wires and other metal constructions. In normal conditions the return current  distributes between these ways in proportion (approx.): main -  90%, secondary –  10%.
When the wire, connecting “+” pin of rectifier and “+” pin of PDU, is disconnected all return current flows through the secondary way. Under this condition the equipment OSN8800 works without mistakes! Diameters of wires (“+”, “-“, “PE”) and their length correspond to project documentation and requirements of Huawei.

Connection between the RTN(+) and the cabinet ground point is (http://support.huawei.com/carrier/docview?nid=SE0000684388#11). In documentation this connection is.

I thought the return current did not flow through the PE-wires. In addition  the dangerous exists to damage the equipment during the storm. Fortunately, until now we have no problems.