IEEE 575-1988 pdf free.IEEE Guide for the Application of Sheath-Bonding Methods for Single-Conductor Cables and the Calculation ofInduced Voltages and Currents in Cable Sheaths.
IEEE 575 Safety precautions and practices in design,construction, operation, and maintenance shouldbe based on the principle that the voltage on theinsulated sheath of a transmission cable may beconsidered analogous to the voltage on the conductor of nonshielded secondary cables.Solidly bonded and grounded sheaths are thesimplest solution to the problem of sheath voltages,and special bonding methods,by which aremeant systems other than solidly bonded andgrounded sheaths,are only justified on the basisof economics (usually at loads above 500 A) or atextremely heavy loads where all heat generationhas to be minimized.
The simplest and most effective method ofspecial sheath bonding is single-point bonding; amajor disadvantage is that maximum cable lengthis governed by the permissible sheath standingvoltage. As a result, when very low limiting valuesof sheath voltage are specified, this method willnot be applicable. Single-point bonding mayrequire a separate groundreturn conductorwhereas cross bonding does not.Of the other bonding systems in use，crossbonding is the most widely used.This system isespecially suitable for long cable lengths.Cable sheaths are usually expected to benominally at ground potential but in a speciallybonded system they may have appreciable volt-ages with respect to ground. Under some cir-cumstances,even solidly bonded and groundedsheaths can be well above ground potential.Someutilities allow sheath standing voltages as high as300 V. With presentday jacket materials, sheathvoltages of 600 V are possible.
Introduction. The sheath of a single-conductor cable for ac service acts as a secondary of atransformer; the current in the conductor inducesa voltage in the sheath. When the sheaths ofsingle-conductor cables are bonded to each other,as is common practice for multiconductor cables,the induced voltage causes current to flow in thecompleted circuit. This current causes losses inthe sheaths. Various methods of bonding may beused for the purpose of minimizing sheath losses.Formerly,where special bonding was employedfor the prevention of sheath losses on lead-sheathed cables without an insulating jacket, thesheaths were subjected to ac voltages,and thebonding was designed to keep the magnitude ofthe induced voltages within small limits so as toprevent the possibility of sheath corrosion due toac electrolysis.
Various levels of permissible sheath voltage toground were proposed at certain times,rangingfrom 12 v to 17 V, to prevent corrosion due toelectrolysis.At the present time, cables are usuallymanufactured with an insulating jacket, so thatinduced voltages no longer constitute a corrosionproblem, and voltages comparable to secondarycable voltages may be acceptable.
The problem of sheath losses becomes particu-larly important when large，single-conductorcables comprising a circuit are placed in separateducts, or spacing between directly buried cables isincreased to reduce the effects of mutual heating,as significantly higher voltages are induced in thecable sheaths. The major purpose of special sheathbonding for single-conductor cables is the prevention or reduction of sheath losses.IEEE 575 pdf download.