Emerson Rosemount SAM42 - Page 28

3.8 Electrical requirements
Mounting the detector on the pipe
• See Temperature considerations for restrictions to ambient and
pipe surface temperatures.
• The sensor shall have galvanic contact with the pipe connected to
PE earth. No paint is allowed at the area of contact.
• The detector housing and mounting socket shall also be
connected to PE earth; either directly through the structure by
removing paint at the area of contact between socket and pipe, or
by other means – e.g., through cable armor (refer to Figure 6-1).
Housing and clamp are in galvanic contact with each other, but
not with the sensor.
Field cable and cable termination
• The recommended field cable for Rosemount SAM42 Ex d version
is 20110626 BFOU(I) M 250V: Shielded twisted two pairs (one pair
for power and one for signal), wire cross-section 0.75 mm
2
, L/R =
87 μH/ohm (max). Color: grey.
• The recommended field cable for Rosemount SAM42 Ex ia version
is 20104969 BFOU(I) M 250V: Shielded twisted two pairs (common
pair for power and signal), wire cross-section 0.75 mm
2
, L/R = 87
μH/ohm (max). Color: blue.
• For Ex-d system, the maximum cable length is 1200 m. This is
limited by use of RS485 communications.
• For Ex-ia systems, the maximum cable length shall be determined
by the installer based upon site requirements (gas group etc.) and
electrical characteristics of the SAM42 device, connecting cable
and communications and power barriers used.
• Note that cables for intrinsically safe apparatus shall be clearly
marked and be clearly identifiable.
• For installations Ex-d, the cable screen shall be connected to PE
earth in the safe area but always left floating on the detector side.
• For installations with IS earth, the cable screen shall be connected
to IS earth in the safe area but always left floating on the detector
side.
• If the detector housing and mounting socket is not in galvanic
contact with the pipe structure, grounding to PE earth must be by
other means, e.g., by terminating the cable armor to the detector
housing and grounding the armor in the safe area. The cable
armor may be terminated within the gland assembly.
Quick Start Guide May2024
28 Emerson.com/Rosemount