FAN1851AN Fairchild Semiconductor, FAN1851AN Datasheet - Page 7
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FAN1851AN
Manufacturer Part Number
FAN1851AN
Description
IC CTRLR AC GRND FAULT 8DIP
Manufacturer
Fairchild Semiconductor
Datasheet
1.FAN1851AN.pdf
(11 pages)
Specifications of FAN1851AN
Applications
*
Mounting Type
Through Hole
Package / Case
8-DIP (0.300", 7.62mm)
Product
Voltage References
Mounting Style
Through Hole
Lead Free Status / RoHS Status
Lead free / RoHS Compliant
Available stocks
Company
Part Number
Manufacturer
Quantity
Price
Company:
Part Number:
FAN1851AN
Manufacturer:
MICROCHIP
Quantity:
2
PRODUCT SPECIFICATION
REV. 2.0.1 6/17/05
C T
=
where:
T = integration time
V = threshold voltage
I = average fault current into CT
therefore:
I
C T
=
----------------------------------------------------------------------------------------------------------------- -
⎛
⎝
input sense
transformer
⎛
⎝
------------------------ -
1000 turns
division of
120
-------- -
500
current generated
=
⎛
⎝
current
1 turn
120 V
------------------------------------ -
(swamps I
0.01 µF
⎞
⎠
heavy fault
⎛
⎝
-------------------- -
1.6
AC
R
B
⎞
⎠
0.4
+
rms
TH
0.4
)
⎞
⎠
charging
⎞
⎠
17.5
on half-
cycles
⎛
⎝
only
CT
⎛ ⎞
⎝ ⎠
----------- -
1000
1
-- -
2
1
current shunted
portion of fault
⎞
⎠
⎛
⎝
around GFI
---------------------- -
RG
⎛ ⎞
⎝ ⎠
1
-- -
2
RN
conversion
+
average
rms to
RN
0.91
0.91
⎞
⎠
0.008
(6)
(7)
In practice, the actual value of C
to include the effects of the neutral loop upon the net charg-
ing current. The effect of neutral loop induced currents is dif-
ficult to quantify, but typically they sum with normal fault
currents, thus allowing a larger value of C
requirements, 0.015µF has been found to be the best com-
promise between timing and noise.
For those GFI standards not requiring grounded neutral
detection, a still larger value capacity can be used and better
noise immunity obtained. The larger capacitor can be accom-
modated because R
full fault current, I, to enter the GFI.
In Figure 10, grounded neutral detection is accomplished by
feeding the neutral coil with 120Hz energy continuously and
allowing some of the energy to couple into the sense trans-
former during conditions of neutral fault.
Transformers may be obtained from Magnetic Metals, Inc.,
(http://www.magmet.com).
N
and R
G
are not present, allowing the
T
will have to be modified
T
. For UL943
FAN1851A
7