Fairford Electronics QFE Series, Manual

Page: 47 / 194

QFE
page 2-23
Electrical Installation
FD8413 issue03_F
2.10.3 Overload Current Profile and Duty Cycle AC-53a
IEC 60947-4-2 Motor Utilisation Category: AC-53a ( not operating in bypass mode)
9
16
23
30
44
59
72
85
— — — —
99 10 35 3
— — — —
99 10 4 5
105
146
174
202
— — — —
99 10 35 3
99 10 6 4
— — — —
242
300
370
500
600
750
900
— — — —
60 3 35 3
60 3 6 4
— — — —
AC-53a overload current profiles applicable to specified models.
Ratio of
On-load period
to total load
(F, %)
Number of
operating
cycles per hour
(S)
Duration of
Overload
(T
x,
seconds)
Overload
Current
(X, multiple
of I
e
)
Model
Numbers
To calculate times for a lower value of current, divide the square of the next highest given
current multiplied by it's given time by the square of the required current.
For example, to find the time, Tx , for X=2.5 x Ie , then Tx = (32 x 35)/(2.52) = 50 seconds.
EXAMPLE IEC RATING INDEX
3 - 35 : 99 - 10 : AC53a : 30A
Rated Operational current (I
e
)
Utilisation Category
For a 99% on-load factor,
and 10 standard operating
cycles per hour, the unit can
accommodate 3 x I
e
for 35
seconds.