MV design guide - Schneider Electric
MV design guide - Schneider Electric
MV design guide - Schneider Electric
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Standards<br />
IEC - ANSI comparison<br />
The following comparison<br />
is based on<br />
different circuit breaker<br />
characteristics.<br />
Overview of the main differences<br />
Theme ANSI IEC<br />
asymmetrical breaking 50% 30%<br />
capacity on faults with current without derating<br />
across the terminals derating<br />
insulation level:<br />
imposes chopped waves<br />
impulse wave<br />
for outdoor equipment<br />
115% Uw/3 s<br />
129% Uw/2 s<br />
short-time withstand 2.7 Isc 2.5•Isc at 50 Hz<br />
current peak<br />
2.6•Isc at 60 Hz<br />
value<br />
2.7•Isc for special cases<br />
Transient Recovery around twice<br />
voltage (1)<br />
as severe<br />
electrical endurance 4 times K.S.Isc 3 times Isc<br />
mechanical endurance 1 500 to 10 000 2 000<br />
according to Ua and Isc<br />
motor overvoltages no text standard test circuit<br />
(1)<br />
the ANSI peak voltage is 10% greater than the voltage defined by the IEC.<br />
The E2/t2 slope is 50% greater than the Uc/t3 slope.<br />
However, the largest part of the graph is the initial part where the SF6 reconstitutes itself.<br />
The two standards easily allow the SF6 to reconstitute itself.<br />
Rated voltages<br />
According to IEC<br />
c Standardised values for Ur (kV): 3.6 - 7.2 - 12 - 17.5 - 24 - 36 kV<br />
According to ANSI<br />
c The ANSI standard defines a class and a voltage range factor K<br />
which defines a range of rated voltages at constant power.<br />
Standardised values for Ur (kV)<br />
class (kV) Umax (kV) Umin (kV) K<br />
Indoor equipment 4.16 4.76 3.85 1.24<br />
7.2 8.25 6.6 1.25<br />
13.8 15 11.5 1.3<br />
38 38 23 1.65<br />
Outdoor equipment 15.5 1<br />
25 1<br />
38 1<br />
100<br />
90<br />
50<br />
10<br />
Upeak (%)<br />
1.2 µs<br />
50 µs<br />
Standardised wave 1.2/50 µs<br />
t (µs)<br />
Rated installation level<br />
According to IEC<br />
Rated Rated lightning Rated power frequency<br />
voltage withstand voltage withstand voltage<br />
(kV) (kV) 50 Hz 1 mm (kV)<br />
7.2 60 20<br />
12 75 28<br />
17.5 95 38<br />
24 125 50<br />
36 170 70<br />
72 Merlin Gerin <strong>MV</strong> Design Guide <strong>Schneider</strong> <strong>Electric</strong>