Endress+Hauser Cerabar M PMC41, Technical Information

Page: 14 / 84

Cerabar M
14 Hauser
Explanation of terms
Explanation of terms: turn down (TD),
set span and span based on zero point
Case 1:
•
⏐
Lower-range value (LRV)
⏐ ≤ ⏐
upper-range value
(URV)
⏐
Example:
• Lower-range value (LRV) = 0 bar
• Upper-range value (URV) = 0.5 bar
• Nominal value (URL) = 1 bar
Turn down:
• Nominal value/
⏐
upper-range value (URV)
⏐
=
1 bar/0.5 bar
TD = 2:1
Set span:
• Upper-range value (URV) – lower-range value (LRV) =
0.5 bar – 0 bar
Set span = 0.5 bar
This span is based on the zero point.
P01-PMx4xxxx-05-xx-xx-xx-001
Example: 1 bar measuring cell
Case 2:
•
⏐
Lower-range value (LRV)
⏐ ≤ ⏐
upper-range value
(URV)
⏐
Example:
• Lower-range value (LRV) = 0 bar
• Upper-range value (URV) = 0.5 bar
• Nominal value (URL) = 1 bar
Turn down:
• Nominal value/
⏐
upper-range value (URV)
⏐
=
1 bar/0.5 bar
TD = 2:1
Set span:
• Upper-range value (URV) – lower-range value (LRV) =
0.5 bar – 0 bar
Set span = 0.5 bar
This span is based on the zero point.
P01-PMx4xxxx-05-xx-xx-xx-002
Example: 1 bar measuring cell
Case 3:
•
⏐
Lower
-range value (LRV)
⏐ ≥ ⏐
upper-range value (URV)
⏐
Example:
• Lower-range value (LRV) = –0.6 bar
• Upper-range value (URV) = 0 bar
• Nominal value (URL) = 1 bar
Turn down:
• Nominal value/
⏐
lower-range value (LRV)
⏐
=
1 bar/0.6 bar
TD 1.67:1
Set span:
• Upper-range value (URV) – lower-range value (LRV) =
0 bar – (–0.6 bar)
Set span = 0.6 bar
This span is based on the zero point.
P01-PMx4xxxx-05-xx-xx-xx-003
Example: 1 bar measuring cell
➀
Set span
➁
Span based on zero point
➂
Nominal value
i
upper-range limit (URL)
➃
Nominal measuring range
➄
Sensor measuring range
LRL Lower-range limit
URL Upper-range limit
LRV Lower-range value
URV Upper-range value
0 bar
+1 bar
URL URV
➂
LRL = LRV
0.5 bar
➃
➁ ➀
=
➄
=
–1 bar
+1 bar
LRV URL URV
➂
0
LRL
0.5 bar
➁ ➀
=
➃
➄
–1 bar
+1 bar
LRV URL URV
➂
0
LRL
–0.6 bar
➁ ➀
=
➃
➄