10
0,7
0,6
0,8
0,9
1
1,1
1,2
1,3
1,4
1,5
Wire
cross section
Ar
ea
[ mm
2
]
0
0,1
0,2
0,3
0,4
0,5
0,20
0,15
0,10
0,05
0
Copper Resistance [ Ω/m ]
Lindab reserves the right to make changes without prior notice
2020-08-05
Lindab reserves the right to make changes without prior notice
2020-08-05
UltraLink Controller
FTCU
lindab | we simplify construction
Power supply
Transformer sizing
The needed size of 24 V AC transformer(s) can be defined by adding up the dimensioning power consumption [VA] of all
the components. The transformer power must exceed this. Use only safety isolating transformers. Calculation of the cur-
rent demand I:
I = (P1+P2+…+P
n
) / U [A]
where:
P
n
is the dimensioned power consumption for each component [VA] U is the voltage
(24) [V].
If the current demand I exceeds 6 A ( which corresponds to approximately 150 VA for a 24 V AC transformer), it is neces-
sary to use more transformers to prevent overheating.
Supply cable sizing
The wire size of the supply cable can be determined by calculating the resistance per meter R. The calculation presup-
poses that a voltage drop of e.g. 2 V is accepted in the supply cable:
R(per m) = U
drop
/ (I * L) [Ω/m]
where:
U
drop
is the accepted voltage drop (2 V) in the cable [V] I is the current [A]
L is the longest distance of supply cables from transformer to a component [m]
Wire cross section area as a function of resistance per m for copper wire
Example:
U
drop
= 2 V, I = 4 A, L = 20 m
R (per m) = 2V / (4A × 20 m) = 0,025 Ω/m
In the diagram a Wire cross section Area of 0,7 mm² can be read.
Power consumption
The power consumption for dimensioning supply cables for an UltraLink
®
FTCU is 3-5 VA.
It is not recommended to use a transformer with a higher capacity than 150 VA.
