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48-651 SIL Certified Safety Manual for E3 Modulevel
®
.• The only unsafe mode is when the unit is reading an
incorrect level within the 4–20 mA range (> ±2% deviation).
• MAGNETROL defines the faulted mode 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).
• The 4–20 mA output signal can be configured for over-
range per NAMUR NE43.
3.1 Miscellaneous Electrical Considerations
Following are miscellaneous electrical issues to be considered
in a safety system.
3.1.1 Pollution Degree 2
The E3 MODULEVEL transmitter is designed for use
in a Category II, Pollution Degree 2 installation, which is
defined by a nonconductive pollution of the sort where
occasionally a temporary conductivity caused by condensation
must be expected.
This is the usual pollution degree used for equipment being
evaluated to IEC/EN 61010.
3.1.2 Overvoltage
The E3 MODULEVEL has overvoltage protection per CE
requirements; this protection is to 1000 volts when consid-
ering Hi-pot, Fast Transients, and Surge. Therefore, there
should be no unsafe failure modes up to 1 KV.
Overvoltage Category II is a local level, covering appliances,
portable equipment, etc., with smaller transient overvoltages
than those characteristic of Overvoltage Category III. This
category applies from the wall plug to the power supply iso-
lation barrier (transformer). The typical plant environment
is Overvoltage Category II, so most equipment evaluated to
the requirements of IEC/EN 61010 are considered to
belong in that classification.
3.1.3 Electromagnetic Compatibility
The E3 MODULEVEl is designed to meet the require-
ments of EN 61326 and NAMUR NE21.
4.0 Mean Time To Repair (MTTR)
SIL determinations are based on a number of factors including
the Mean Time To Repair (MTTR). The analysis for the E3
MODULEVEL is based on a MTTR of 24 hours.
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