Schweitzer Engineering Laboratories SEL-351 - Power Element Accuracy

1-20 Introduction and Specifications Date Code 20001006
SEL-351 Instruction Manual
MW / MVAR
(A, B, C, and 3-phase; 5 A nominal;
wye-connected voltages)
Accuracy
(MW / MVAR) at load angle
for 0.5 A s £ phase current < 1.0 A s:
0.70% / - 0° or 180° (unity power
factor)
0.75% / 6.50% ±8° or ±172°
1.00% / 2.00% ±30° or ±150°
1.50% / 1.50% ±45° or ±135°
2.00% / 1.00% ±60° or ±120°
6.50% / 0.75% ±82° or ±98°
- / 0.70% ±90° (power factor = 0)
for phase current ³ 1.0 A s:
0.35% / - 0° or 180° (unity power
factor)
0.40% / 6.00% ±8 or ±172°
0.75% / 1.50% ±30° or 150°
1.00% / 1.00% ±45° or ±135°
1.50% / 0.75% ±60° or ±120°
6.00% / 0.40% 82° or ±98°
- / 0.35% ±90° (power factor = 0)
Metering accuracy calculation example for currents I
A
, I
B
, and I
C
due to preceding stated tem-
perature coefficient:
For temperature of 40°C, the additional error for currents I
A
, I
B
, and I
C
is:
[(0.0002%)/(°C)
2
] · (40°C - 20°C)
2
= 0.08%
Power Element Accuracy
Pickup: ±0.005 A · (voltage secondary) and ±5% of setting at unity power factor {1 A nom}
±0.025 A · (voltage secondary) and ±5% of setting at unity power factor {5 A nom}
Courtesy of NationalSwitchgear.com