There is no problem with using the Canalis KTA, KTC & KH  trunking in DC.

Determination of direct current that can be conveyed:

The power conveyed in a busbar trunking is limited by the maximum permissible temperature rise.
In standard AC three-phase conditions, distribution is considered to be balanced and the current in the neutral is thus estimated equal to zero. Power loss in heat form = Pac= 3x R x Iac²
(R= resistance of a conductor, Iac = rms current in conductor)
In DC conditions, if we consider 1 conductor for the + and 1 conductor for the -, power loss for 4 conductors = Pdc = 4 x R x Idc² (Idc = direct current) Total power loss in heat form must remain constant: Pac = Pdc

- Case with 1 conductor for the + and 1 conductor for the ? (2 possible circuits in the same busbar trunking) Idc=1,7320/2 xIac=0.866xIac
- Case with 2 parallel conductors for the + and 2 parallel conductors for the - (1 circuit in the same busbar trunking) Idc=1,732xIac

• Electrodynamic effect:

According to the prospective short-circuit peak current, bars must be interlaced (phase1//phase3; phase 2// neutral) to distribute more evenly electrodynamic forces during short-circuit faults.
If the DC short-circuit peak current is equivalent to or greater than the standard short-circuit peak current, interlacing is necessary
If the DC short-circuit peak current is less than the standard peak short-circuit current, contact us to evaluate the electrodynamic forces generated

• Voltage drops :

The voltage drop depends on the length of line L for the return journey. Only the hot resistance per metre R1 given in the catalogue and the DC nominal current, ldc, by circuit must be taken into account

- Case with 1 conductor for the + and 1 conductor for the - (2 circuits available in one busway)
- Case with 2 parallel conductors for the + and 2 parallel conductors for the ? (1 circuit available in one busway)

• Protection:

In DC, there is no move to zero of voltage and current to favour extinguishing of the protective device arc. Arc time is longer and there is more energy to absorb than in AC. DC arc voltage must very quickly rise to the value of the source voltage to extinguish the short- circuit current.

Reduced electrical equation: U network = R x Isc + Uarc Isc
=> (U network -Uarc) / R = Isc
Isc = 0 when Uarc = U network

Rapid increase in arc voltage is possible by the placing in series of fuse protection devices: one fuse on the + and one fuse on the - of each circuit.

For certain operational current and fuse characteristics, it may be necessary to implement two fuses connected in series by polarity (highly inductive circuit). In some cases, two fuses must be connected in parallel by polarity.  According to applications, the standard enclosures supplied with only three fuse bases cannot therefore always be used

Released for:Schneider Electric UK