VEGA 912X-IS FISCO POWER SUPPLIES - Manual

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May 2003
912X-IS FISCO POWER
SUPPLIES
FSC-MBT Te rm in ato r
Relcom Inc.
4
5
6
7
8
3
1
2
POWER
Relcom Inc.
FCS-MB8-SG
POWER
FCS-MB4-SG
4
3 1
2
Relcom Inc.
Relcom Inc.
POWER
FCS-MB4-SG
4
3 1
2
Relcom Inc.
POWER
FCS-MB4-SG
4
3 1
2
Relcom Inc.
POWER
FCS-MB4-SG
4
3 1
2
Relcom Inc.
POWER
FCS-MB4-SG
4
3 1
2
Relcom Inc.
FSC-MBT Te rm in ato r
Relcom Inc. FSC-MBT Te rminator
Safe or Zone/Division 2
hazardous area
9122-IS
FISCO power
supply, IIB
9121-IS
FISCO power
supply, IIC
AC power 85 - 265Vac
Zone/Division 1
hazardous area
IIC IIB
8914-PS-AC
power
supply
8914-PS-AC
power
supply
Safe area
OVERVIEW
The 9121-IS and 9122-IS are fieldbus repeater isolators which repeat
the fieldbus signal from a safe area, Zone 2 or Division 2 fieldbus to
an intrinsically safe fieldbus for connection to devices in Zone or
Division 1. The 9121-IS provides up to 110mA, typically powering up
to 5 x 20mA field devices in Gas Group IIC and the 9122-IS provides
up to 250mA, typically powering up to 12 x 20mA field devices in
Gas Group IIB.
The 912x-IS is certified to FISCO (Fieldbus Intrinsically Safe COncept)
based on the Fieldbus FOUNDATION FF816-FISCO physical layer
profile and IEC/TS 60079-27 FISCO Technical Specification. This
allows the power supplied to the IS fieldbus to exceed the limit set in
the original FF-816 IS physical layer profile. This increases the number
of devices on an IS fieldbus from typically 4 x 20mA devices with
maximum of 80m cable run, to up to 12 x 20mA devices with 250m
cable run using the 9122-IS.
In addition, FISCO reduces the documentation required. Intrinsically
safe systems have been installed in accordance with IEC/EN60079-
14 or similar local code of practice. This requires:
◆ calculation of cable parameters
◆ comparison of safety descriptions
◆ creation of descriptive system document
The administrative work involved in carrying this out in accordance
with the end users procedures is usually considerable. Simply adding a
new field device to an IS segment will require all this documentation to
be updated.
Fieldbus intrinsically safe systems can now also be installed in
accordance with IEC/TS 60079-27 FISCO Technical Specification.
This:
◆ eliminates need to calculate cable parameters
◆ reduces safety documentation to a list of devices
◆ allows addition of devices without a review of safety
documentation
◆ as proven by test, allows longer cables with higher
capacitance
To install a fieldbus system to IEC/TS 60079-27 FISCO Technical
Specification, the cable used in the system must comply with the
following parameters:
Loop resistance Rc: 15 to 150 Ω/km
Loop inductance Lc: 0,4 to1 mH/km
Capacitance Cc: 80 to 200 nF/km
Maximum length of each spur cable: 30 m in IIC and IIB
Maximum length of each trunk cable: 1 km in IIC 5 km in IIB
When cable which complies with this specification is used, no further
consideration of cable parameters is necessary. Virtually any
instrument cable suitable for a fieldbus signal will comply.
Alternatively if all these cable requirements are not met on a segment,
the FISCO power supplies can still be used in intrinsically safe systems,
calculating the cable parameters to IEC/EN60079-14 in the usual
way.
Fieldbus Foundation™ and FOUNDATION™ are trademarks of Fieldbus Foundation, Austin, Texas, USA.