Siemens LC 500 사용자 설명서
Page 12
SITRANS LC 500 – INSTRUCTION MANUAL
7ML19985GE01
mmmm
m
Oper
at
ion & Appl
icat
ion
The entire SITRANS LC 500 transmitter is potted in epoxy resin as part of the intrinsic
safety protection. The potting also protects the electronics against mechanical vibration
and moisture influences.
The transmitter is connected to the electrode by a mini coaxial cable, and grounded to a
connection point inside the enclosure. The external ground lug on the enclosure provides
a means of connecting the instrument system ground to a grounded tank or stilling well
safety protection. The potting also protects the electronics against mechanical vibration
and moisture influences.
The transmitter is connected to the electrode by a mini coaxial cable, and grounded to a
connection point inside the enclosure. The external ground lug on the enclosure provides
a means of connecting the instrument system ground to a grounded tank or stilling well
1
.
(For more detailed information on grounding requirements, please see Grounding
Examples, page 28.)
The measuring range of the SITRANS LC 500 is 3300 pF (1.0 pF
Examples, page 28.)
The measuring range of the SITRANS LC 500 is 3300 pF (1.0 pF
≅
10
–12
F).
Application: SITRANS LC 500
The SITRANS LC 500 provides an analog and a solid-state output. The analog output can
be either a continuous signal proportional to the reading, or in 2-state mode, a mA signal
operating according to NAMUR recommendations for fault signalling
be either a continuous signal proportional to the reading, or in 2-state mode, a mA signal
operating according to NAMUR recommendations for fault signalling
2
.
0% (LRV) and 100% (URV) can be set anywhere within the measurement range.
1.
The loop current provides either:
a. an analog signal:
• a reading proportional to level (PV) under normal conditions
• an out-of-limits display, ‘ooL’, alternating with PV, in fault conditions (if the
• an out-of-limits display, ‘ooL’, alternating with PV, in fault conditions (if the
process level exceeds the limit settings [USL] or [LSL])
or:
b. in 2-state mode, provides a mA output:
• 4 mA or 20 mA output for 0% and 100%, under normal conditions
• a 3.6 or 22 mA output in fault conditions (when 2-state fault signalling
• a 3.6 or 22 mA output in fault conditions (when 2-state fault signalling
[menu 08] is enabled, if the process level exceeds the limit settings [USL or
LSL])
LSL])
2.
The solid-state output can be set to ‘contact open’ or ‘contact closed’, relative to a
covered probe: it can be wired to an external relay and used to activate an external
alarm or a pump via an auxiliary power circuit. It can be activated under normal
conditions by the threshold settings, or Fault signalling can be enabled at menu 18.
alarm or a pump via an auxiliary power circuit. It can be activated under normal
conditions by the threshold settings, or Fault signalling can be enabled at menu 18.
1.
Where the stilling well is welded to the tank.
Note:
For safety purposes, and to ensure reliable measurement signals, the external
ground lug provided on the SITRANS LC 500 enclosure must be firmly connected by an
adequate cable to the grounded vessel or stilling well
adequate cable to the grounded vessel or stilling well
.
2.
See page 93 for detailed examples.