4
ORI-652 Jupiter
®
Model JM4 Magnetostrictive Transmitter – SIL Safety Manual
• Table 3 is used to determine the achievable SIL as a function of
the Hardware Fault Tolerance (HFT) and the Safe Failure Frac-
tion (SFF) for the complete safety function (Type B — complex
components as per IEC 61508 Part 2) of which the level transmit-
ter is one component.
2.0 Level Measuring System
The diagram at left shows the structure of a typical measuring
system incorporating the JUPITER Model JM4 transmitter.
This SIL-rated device is only available with an analog signal
(4–20 mA) with HART communications, and the measurement
signal used by the logic solver must be the analog 4–20 mA
signal proportional to the level.
• For fault monitoring, the logic unit must recognize both high
alarms (≥ 21.5 mA) and low alarms (≤ 3.6 mA).
• If the logic solver loop uses intrinsic safety barriers, caution must
be taken to ensure the loop continues to operate properly under
the low alarm condition.
• The only unsafe mode is when the unit is reading an incorrect
level within the 4–20 mA range (> ±2% deviation).
• MAGNETROL defines a safe failure as one in which the
4–20 mA current is driven out of range (i.e., less than 3.8 mA
or greater than 21.5 mA).
2.1
Miscellaneous Electrical Considerations
Following are miscellaneous electrical issues to be considered in a
safety system.
2.1.1 Pollution Degree 2
The JUPITER Model JM4 transmitter is designed for use in a
Category II, Pollution Degree 2 installation, which is defined
by the non-conductive pollution of the sort where occasionally
a temporary conductivity caused by the condensation must be
expected.
This is the usual pollution degree used for equipment being
evaluated to IEC/EN 61010.
2.1.2 Over-voltage
The JUPITER Model JM4 transmitter has, as standard,
over-voltage protection per CE requirements. When considering
Hi-pot, Fast Transients, and Surge, this protection is to 1000
volts (1KV). Therefore, there should be no unsafe failure modes
up to 1 KV.
PACTware
TM
with
Jupiter® x.x DTM
HART Modem
Actuator
Jupiter
®
Model JM4
Logic
Unit
