Answer / sivasubramanian

U0 is the r.m.s. value between any insulated conductor and
earth , i.e. metal covering of the cable or the surrounding
medium;
U is the r.m.s. (root mean square voltage) value between
any two phased conductors of a multicore cable or of a
system of single core cables.

Answer / jeffrey tay

U0 is the rated power frequency voltage between conductor
and earth or metallic screen for which the cable is designed

U is the rated power frequency voltage between conductors
for which the cable is designed

Um is the maximum value of the “highest system voltage” for
which the equipment may be used (see IEC 60038)

Answer / lalit

Uo is the phase ground voltage and
U is the phase - phase voltage

Answer / kannan

Rated voltage is a reference voltage used for cable design
and electrical property test, and identified with Uo/U and
Um in the standard. The meaning of the symbols is defined as
per JB/T 8996.
Uo一Virtual value of the rated voltage between conductor
used for cable design and metallic shield or metallic
sheath, kV;
U一Virtual value of the rated voltage between conductors
used for cable design, kV;
Um一Virtual value of the highest working voltage for
equipment, kV.
In the standard: Uo/U=64/110
Um=126

Answer / essam s. salib

Uo in under ground cables is the voltage between any phase and the sheath surrounding the cable, while Uo in OH lines is the voltage between any phase and the ground through the line stray capacitance.
U is the voltage difference between any two phases either cables or OH lines.
Um is the maximum operating line voltage between phases

Answer / jeffrey tay

U0 is the cable conductor and shield design with metal
cover layer or between the rated power frequency voltage; U
is a cable designed for use between conductors rated
frequency voltage (three-phase line voltage); Um is the
maximum operating voltage of the system; Up is cable
designed for use in each line of core and shield or metal
sleeve Lightning impulse withstand voltage between the
peak.
U0 value is based on cable systems where the single-phase
ground fault occurs when the duration of the permit
determined. In the GB 12706. 1 -91 stipulated in the two
types of cables: Category 1 cables, U0 for 21 kV, for each
single-phase ground fault time is not greater than 1 min of
the system can be used for single-phase ground fault time
of the most length of no more than 8 h, an annual total of
no more than 125 h of the system; Class 2 cable, U0 for 26
kV, for a longer ground fault systems, and cable insulation
performance requirements for high occasions.

Answer / will

U -means the voltage at that instance.
Uo-means the nominal voltage or design voltage.

Answer / hemant choudhary

U0-Rated voltage
U-Peak Voltage

Answer / minku

Uo refers to the fault voltage in the unfaulted phases in
case of non-effectively grounded sysytem and U refers to
the fault voltage in the case of solidly grounded system.

Answer / hemant choudhary

U0-Rated Voltage
U-RMS Voltage

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