Data Sheet for Product

RL 243 A Commercial Duty Analog Relay Technical Instructions
Document Number 155-107P25
Rev. 1, April, 2000
Siemens Building Technologies, Inc.
Page 9
Figure 13. Lowest Pressure Signal
Selector.
OPERATIONAL FORMULA:
TD + (T – TR) = R. Since T and TR are zero,
then TD = R if S > TD, or S = R if S < TD.
R cannot be greater than S.
Operation,
Continued
Lowest Pressure Signal
Selector
Output pressure will equal the lower of the two input pressures.
Figure 14. Signal Inverting Relay.
OPERATIONAL FORMULA:
T – TR = R Since TD = 0 and S = TR
S = R if S< 1/2 T. T – TR = R if S > 1/2 T.
R cannot be greater than S, and T – TR cannot be
less than 0 psig.
Signal Inverting Relay
Output pressure will equal input pressure until output reaches one-half of T port
pressure. At this point an increase in input pressure causes an equal decrease in output
pressure.
Input # 1 Input # 2 Output
S (psig) TD (psig) R (psig)
25 0 0
0 25 0
15 6 6
3 10 3
Air Input Output
Supply S & TR R
T (psig) (psig) (psig)
18 3 3
18 9 9
18 15 3
18 18 0
25 3 3
25 12.5 12.5
25 15 10
25 15 0
Discontinued