Emerson Micro Motion Installation Manual page 18

Wiring
Table 3-3:
Input parameters
Voltage (U
Current (I
Internal capacitance (C
Internal inductance (L
Output parameters
Voltage (U
Current (instantaneous) (I
Current (steady state) (I)
Power (P
Internal resistance (R
Cable parameters for Group IIC
External capacitance (C
External inductance (L
External inductance/resistance ratio (L
Cable parameters for Group IIB
External capacitance (C
External inductance (L
External inductance/resistance ratio (L
Hazardous area
voltage
Hazardous area
current
Hazardous area
capacitance
Hazardous area
inductance
14
RS-485 output and cable entity parameters (MTL7761AC)
)
i
)
i
)
i
)
i
)
o
)
o
)
o
)
i
)
o
)
o
)
o
)
o
The meter entity parameters require the selected barrier's open-
circuit voltage to be limited to less than 30 VDC (Vmax = 30 VDC).
The meter entity parameters require the selected barrier's short-
circuit currents to sum to less than 484 mA (Imax = 484 mA) for all
outputs.
The capacitance (Ci) of the meter is 0.0011 μF. This value added to
the wire capacitance (Ccable) must be lower than the maximum
allowable capacitance (Ca) specified by the safety barrier. Use the
following equation to calculate the maximum length of the cable
between the meter and the barrier: Ci + Ccable ≤ Ca
The inductance (Li) of the meter is 0.0 μH. This value plus the field
wiring inductance (Lcable), must be lower than the maximum
allowable inductance (La) specified by the safety barrier. The
following equation can then be used to calculate the maximum cable
length between the meter and the barrier: Li + Lcable ≤ La
18 VDC
100 mA
1 nF
0.0 H
9.51 VDC
480 mA
106 mA
786 mW
19.8 Ω
85 nF
154 µH
/R ) 31.1 µH/Ω
o o
660 nF
610 µH
/R ) 124.4 µH/Ω
o o
Micro Motion Specific Gravity Meters