
Hardware
Installation
4 - 8
SKF Multilog O
n-Line System IMx-M
User Manual
Important - SKF USB isolator cables shall always be used when connecting to
IMx-M USB ports.
Important - Equipment connected to buffered outputs must be isolated from
the protective earth.
Important - IGND signals should be connected to protective earth/ground at
one point only.
Important - An IMx-M rack must be connected to protective earth since surge
suppressors are connected between network terminals and protective earth.
Signal Isolation
Galvanic isolated parts (Maximum allowed voltage difference relative to protective earth
is 40 V):
•
4–20 mA output block (not individually isolated)
•
Ethernet ports (individually isolated)
•
Protection redundant Modbus RS485 L1, L2 (individually isolated)
•
All relays are potential free relays (individually galvanic isolated).
•
Digital inputs D1-D8 are optically isolated inputs (individually isolated)
•
Disarm input (Note: shared ground terminal with RS485, L2)
Electrical isolated parts, differential inputs:
•
Analog inputs are differential inputs and support common mode up to
25 V
relative to IGND.
•
Condition Monitoring RS485, L3. See Signal Grounding for details regarding L3
ground terminal.
Parts relative to Instrument Ground IGND (should be used with care to prevent ground
loops, see also Signal Grounding:
•
Buffered outputs (connect only
to isolated /differential inputs).
•
USB ports are relative to instrument ground.
Important - Signal grounding procedure must be handled with special care to
avoid ground loops. Be sure to read "Signal Grounding" chapter thoroughly and
understand it.