Fisher 00275-8026-0001 Manuale Utente
C-2
FACTORY MUTUAL (FM)
The FM entity parameters listed in Table 1 only apply to associated
apparatus with linear output.
apparatus with linear output.
.
Before connecting the model 275 into the loop, determine the connected
inductance of the system by adding the L
inductance of the system by adding the L
i
of the transmitter and cable.
The sum must be less than the L
a
, as determined from Table 2, before the
275 can be connected into the loop.
If the connected inductance is greater than the value determined from the
table, a barrier with a lower I
table, a barrier with a lower I
sc
must be chosen.
Table 1: FM Entity Parameters
Input Parameters
Class I, Div. 1, Groups A, B, C, D
V
max
= 30 V
dc
V
T
or V
oc
of barrier must be < 30 V
dc
I
max
= 300
m
A
I
T
or I
sc
of barrier must be < 300
m
A
C
i
= 0.07
µ
F
C
A
of barrier must be > 0.07
µ
F
L
i
= 0
m
H
L
A
of barrier must be > 0
m
H
Output Parameters
V
oc
= 1.7 V
dc
N/A
I
sc
= 32
m
A
N/A
Table 2: Maximum Allowable Connected Inductance
I
m
La (
m
H)
(
m
A)
Groups
A & B
Group
C
Group
D
300
0.20
1.80
3.20
280
0.21
2.00
3.70
270
0.23
2.20
3.90
260
0.25
2.50
4.30
250
0.27
2.70
4.60
240
0.30
3.00
5.00
220
0.40
3.20
5.90
200
0.50
4.00
7.20
180
0.60
5.00
8.80
00275-0081
DWG No.
Rev. D.
Sheet 1 of 2