x/EN AP/Na7
-46 MiCOM P74
• Compensated:
− Minimum two phase busbar fault current
− Maximum single-phase steady state busbar fault current
− Maximum load current on the biggest feeder
− Optional: Maximum three phase busbar fault current
• With impedance:
− Minimum two phase busbar fault current
− Minimum single phase to earth busbar fault current
− Minimum load current on the smallest feeder
− Maximum load current on the biggest feeder
− Optional: Maximum three phase busbar fault current
− Maximum substation short-circuit withstand time
7.4 Switchgear
• Nominal CT ratio
• Highest nominal primary current (CT In Max)
• Lowest nominal primary current (CT In Min)
• CT Knee point voltage (Vk) for each CT
• CT secondary resistance (RCT) for each CT
• Length and cross section of the conductors between each CT and the peripheral unit.
(In the absence of precise information, an estimate taken from the lowest CT ratio will
suffice)
• Auxiliary contacts of disconnecting switches and tripping orders for circuit breaker failure
(irrespective of the how the CB fail scheme is to be implemented i.e. internally or
externally initiated)
7.5 Cubicle specifications
• Cubicle specification is contract specific.
• However, GE propose the following:
• Single cubicle: 800x800x2000
• Double cubicle: 1600x800x2000
• Model: Schroff type Proline
• Colour: RAL 7032
1 P741 and P742:
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