Calculations > Protection > Protection for Enexis

Prior to analysis, loadflows can be performed. A normal load flow and load flows with failure of one transport cable at a time.

Protection settings can be checked against items from the prescribed tactics.

Analysis consists of making short-circuits. Short circuits are simulated at all nodes and in all cables and connections. The function simulates blunt short circuits of various kinds.

Pdf diagrams of the transmission network and distribution directions can be generated.

Setup forms can be generated.

Options

In the Options (Calculation | Limits), normal limits and fault limits must be specified.

In the Options (Calculation | Grid Analysis | Enexis Security), the default number of parallel transmission cables p, the stagger time and the location of the adjustment forms must be specified.

Terminology

Transport

Transport nodes and cables are determined automatically.

A transport cable is a mesh cable.

A transport node is a node that has at least one mesh cable attached to it or an unsecured link to such a node.

Itoe

TheItoe (It Allowable) is a quantity that Enexis assigns to cables. It is a kind of extendedInom.

TheItoe of a distribution cable is the minimum of:

•TheInom' of the cable * 1.3

•TheInom of the current measuring transformer * 1.2

•TheInom of the load switch

•The trip current of the fuse / 1.5

•TheInom of the circuit breaker

•The trip current of the current protection device / 1.5 or 1.3 (1.5 for mechanical; 1.3 for electronic)

•The I> of the distancing protection / 1.5 or 1.3 (1.5 for mechanical; 1.3 for electronic)

TheItoe of a transport cable is the minimum of:

•The smallestInom' * pf of the cable sections * 1.45 * 1.07

•TheInom of the current measuring transformer * 1.2

•TheInom of the load switch

•The trip current of the fuse / 1.5

•TheInom of the circuit breaker

•The trip current of the current protection device / 1.5 or 1.3 (1.5 for mechanical; 1.3 for electronic)

•The I> of the distancing protection / 1.5 or 1.3 (1.5 for mechanical; 1.3 for electronic)

pf is a factor based on p from the options and the cable type (GPLK or XLPLE (actually non-GPLK)).

For GLPK, pf(p) is 1.00; 0.80; 0.66; 0.62; 0.58; 0.55; 0.54; 0.52; 0.51; 0.49.

For XPLE, pf(p) is 1.00; 0.84; 0.74; 0.69; 0.65; 0.61; 0.59; 0.57; 0.55; 0.53.

A mechanical relay is a relay with one of the following texts in its type name or short type name:

SD14, SD34, LI41, ISM, MU1, BMA311, WIpx, HK, HB, MWD, BMA, RACID, RACIF, R3A or OT87.

General

General