Siemens LMV 5 Series, Technical Instructions, Page: 337 / 374

LMV Series Technical Instructions
Document No. LV5-8000
SCC Inc. Page 7 Appendix A
Hot Standby on a Steam Boiler with an RWF50 or RWF55
Introduction
Hot standby is recommended on multi-boiler systems to maintain one or more backup boilers
close to operating temperature. Hot standby can be accomplished on an LMV5 with an RWF5x
controller. The procedure and operation will be described for the following two methods:
•
LMV5 with an RWF5x for hot standby control only
•
LMV5 with an RWF55 for hot standby and load control
Table 2 describes the six different load controller operating modes in the LMV5.
Table 2: Description of LMV5 Load Controller Operating Modes
Label Description Setpoint
Upon X62.1 – X62.2
Contact Closure
ExtLC X5-03
External load control,
firing rate from
3-position input
N/A
Change to “IntLC”,
setpoint W1
IntLC
Internal load control,
setpoint set locally on
LMV5
W1
Remain in “IntLC”,
setpoint W2
IntLC Bus
Internal load control,
setpoint from Modbus
command
W3
Change to “IntLC”,
setpoint W1
IntLC X62
Internal load control,
setpoint from analog
signal on terminal X62
Remote
setpoint
ExtLC X62
External load control,
firing rate from analog
signal on terminal X62
N/A
ExtLC Bus
External load control,
firing rate from Modbus
command
N/A
If any operating mode other than “IntLC” is used, a contact closure between terminals X62.1
and X62.2 will cause the LMV5 to revert back to operating mode “IntLC”. This is necessary to
achieve hot standby on an LMV5 using the RWF5x to control the hot standby only.
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