ABB PQFA, Instruction Manual

Page: 31 / 98

PQFA Instructions Manual
Asea Brown Boveri Jumet S.A.
31
Example n°2:
PQFA-A 155A 480V 60hz
Step 1: I
N
= 155A
?
cable section (*) = 70 [mm
2
]
Step 2: multiplication factor for a 70 [mm
2
] copper cable at 60hz = 1.13
Step 3: I = I
N
x 1.13 = 155A x 1.13 = 175 A
Step 4: I = 175A
?
cable section (*) : 95 [mm
2
]
Step 5: multiplication factor for a 95 [mm
2
] copper cable at 60hz = 1.21
Step 6: I = I
N
x 1.21 = 155A x 1.13 = 187,5 A
Step 7: I = 187,5A
?
cable section (*) : 95 [mm
2
]
This section is equal to the section found in the previous step.
Result : one copper cable of 95 [mm
2
] per phase
Example n°3:
PQFA-B 427A 400V 50hz
Step 1: I
N
= 427A
?
cable section (*) = 300 [mm
2
]
Step 2: multiplication factor for a 300 [mm
2
] copper cable at 50hz = 1.70
Step 3: I = I
N
x 1.70 = 427 A x 1.70 = 726 A
Step 4: I = 726A
?
cable section (*) : 2 x 185 [mm
2
]
Step 5: multiplication factor for a 185 [mm
2
] copper cable at 50hz = 1.41
Step 6:
I = I
N
x 1.41 = 427A x 1.41 = 602 A
?
which means 301 A per cable
Step 7: I= 301 A
?
cable section (*) : 185 [mm
2
]
This section is equal to the section found in the previous step.
Result : two copper cable of 185 [mm
2
] per phase
(*) given for information only.