Yokogawa RotaMASS 3-Series - Manual (Page 99)

9. EXPLOSION PrOTECTEd TyPE INSTrUMENTS
9-23
IM 01R04B05-00E-E 3rd edition July 30, 2010 -00 all Rights Reserved. Copyright © 2005, Rota Yokogawa
9.3.6 I.S. fieldbus system complying with FISCO (only /EF4)
the criterion for such interconnection is that the voltage (ui), the current (Ii) and the power (Pi), which in-
trinsically safe apparatus can receive, must be equal or greater than the voltage (uo), the current (Io) and
the power (Po) which can be provided by the associated apparatus (supply unit).
Po ≤ Pi, uo ≤ ui, Io≤ Ii.
In addition, the maximum unprotected residual capacitance (Ci) and inductance (Li) of each apparatus (other
than the terminators) connected to the fieldbus line must be equal or less than 5 nF and 10 µH respectively.
Ci ≤ 5 nF, Li ≤ 10uH
Supply unit
the supply unit must be certified by a notify body as FISCo model and following trapezoidal or rectangular
output characteristic is used.
uo = 14... 17.5 V (I.S. maximum value)
Io based on spark test result or other assessment,
ex. 133 ma for uo = 15 V (Group IIC, rectangular characteristic)
no specification of Lo and Co in the certificate and on the label.
Cable
the cable used to interconnect the devices needs to comply with the following parameters:
loop resistance R’: 15...150 Ω/km
inductance per unit length Lc: 0.4...1 mH/km
capacitance per unit length Cc: 80...200 nF/km
C’ = C’ line/line + 0.5 C’ line/screen, if both lines are floating
or
C’ = C’ line/line + C’ line/screen, if the screen is connected to one line
length of spur cable: max. 30 m (IIC and IIB )
length of trunk cable: max. 1 km (IIC) or 5 km (IIB)
Terminators
the terminator must be certified by a notified body as FISCo model and at each end of the trunk cable an
approved line terminator with the following parameters is suitable:
R = 90...100 Ω
C = 0...2.2 µF (0.8 ... 1.2 µF is required in operation)
the resistor must be infallible according to IEC 60079-11.
Number of devices
the number of devices (max. 32) possible on a fieldbus link depends on factors such as the power con-
sumption of each device, the type of cable used, use of repeaters, etc.
9.4 INMETrO (Brazil)
RCCS3x with option /uS1 same as IECEx /ES1
RCCt3x with options /uF3 ... /uF4 same as IECEx EF3 ... /EF4
RCCR31 with options /uF3 ... /uF4 same as IECEx EF3 ... /EF4
Same parameters and specifications as IECEx approval. See chapter 9.3.
9.5 Gost Approval
Rota Yokogawa has the “Pattern approval Certificate of
Measuring Instruments” which allows to export the instrument to Russia, Kazakhstan, uzbekistan and other
CIS countries. Furthermore RotaMaSS is Rtn (GGtn) approved for
installation in hazardous areas. For the export of RotaMaSS to CIS countries please contact your
Yokogawa representative
.