Siemens HydroRanger 200 HMI - Setting Zero Head

Operating
7.12 Open Channel Monitoring (OCM)
HydroRanger 200 HMI
Operating Instructions, 06/2018, A5E36281317-AC
139
7.12.2
Setting Zero Head
Many PMDs start flowing higher than the traditional empty distance of the application. You
can account for the flow in one of two ways:
1. Use Zero Head (2.13.4.5) (Page 244) to have OCM calculations ignore levels below that
value. Possible head = Span (2.2.2.) (Page 169) minus Zero Head (2.13.4.5.) (Page 244)
Note
Maximum Head (2.13.4.2.)
(Page 243) is preset to Span (2.2.2.) (Page 169) , and is not
updated when
Zero Head (2.13.4.5.) (Page 244) is used. Make sure you set Maximum
Head (2.13.4.2.)
(Page 243) to the correct value when using Zero Head (2.13.4.5.)
(Page
244)
①
α
④
Zero Head (2.13.4.5.) (Page 244)
②
Empty (2.2.4.) (Page 170)
⑤
Maximum Head (2.13.4.2.) (Page 243)
③
Span (2.2.2.) (Page 169)
2. Use Range Extension (2.2.7.) (Page 172) where the Empty (2.2.4.) (Page 170) level is
set to the bottom of the weir, and above the bottom of the channel. It should be used if
the surface monitored can fall past the Empty level in normal operation without reporting
an LOE. The value in Range Extension (2.2.7.) (Page 172) is added to Empty (2.2.4.)
(Page 170) and can be greater than the range of the transducer.