ISA T 2000 - Page 70

DOC. MIE11110 Rev. 5
Page
70
of
110
In this case, the voltage is applied between A and N on the HV
side, and it is measured between a and c on the secondary side.
The measured ratio is therefore:
T = VAN / Vac = (VAB / 1,732) / Vac = (VAB / Vac ) / 1,732
= t / 1.732,
hence:
t = T * 1,732
The software multiplies the ratio by 1.732, and displays the actual
ratio.
Case 3: Type Dy
Voltage is applied between A and C on the HV side, and it is
measured between a and n on the secondary side. The measured
ratio is therefore:
T = VAC / Van = VAC / ( Vac / 1,732 ) = (VAC / Vac ) *
1,732 = t * 1.732,
hence:
t = T / 1,732
The software divides the ratio by 1.732, and displays the actual
ratio.
The connection diagram is the following.