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POWERS
RL 243 MP Multi-Purpose Relay
Description
Product Number
Operation
®
Controls
The Powers RL 243 MP Multi-Purpose Relay is a pneumatic auxiliary device designed to
provide a variety of pneumatic control functions for the typical control system.
Applications include direct and reverse acting amplifying, signal advancing, minimum
pressure relay, and lower pressure transfer. (See Figures 2 through 10.)
The relay operates on a force balance principal and is provided with a Powers two-valve
design to assure stability and prevent unnecessary air consumption. Internal relief
assembly prevents signal lock-up and assures fail-safe operation. The relay housing is
provided with integral brackets to facilitate installation without a separate bracket.
A single spring adjustment is provided to allow setting the relay for desired operation.
The relay is adaptable for flush panel mounting to facilitate manual readjustment if
desired.
243-0009
The relay output pressure at port R is dependent upon the adjustable setting of spring
S1, the interaction of pneumatic signals at ports TD and TR, and the availability of a
supply source at port S. The basic relay formula can be expressed as follows:
NOTE:
(S
- TR) cannot be less than zero,
1
Where:
R
is the output pressure
TD
is a direct acting input variable
S
is the setting of the adjustment spring
1
TR
is a reverse acting input variable (opposing S
Technical Instructions
Document No. 155-042P25
R = (TD + (S
- TR) = S
1
)
1
RL 243-6
September 10, 2018
Siemens Industry, Inc.
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Summary of Contents for Siemens POWERS RL 243 MP
- Page 1 RL 243 MP Multi-Purpose Relay Description The Powers RL 243 MP Multi-Purpose Relay is a pneumatic auxiliary device designed to provide a variety of pneumatic control functions for the typical control system. Applications include direct and reverse acting amplifying, signal advancing, minimum pressure relay, and lower pressure transfer.
-
Page 2: Specifications
Within 0.25 psi (1.7 kPa) Relief valve differential Within 1.0 psi (6.89 kPa) Accessories Panel mounting For flush mounting, with adjustable knob, dial plate and mounting bracket Surface bracket For exposed surface mounting (Use with Panel Mounting Kit above) Page 2 Siemens Industry, Inc. - Page 3 Output pressure will vary directly with input pressure. Relay is fail-safe and cannot Amplifying Relay generate an output signal unless a source of air is available at S-port (Figure 2). Figure 2. Direct Acting (DA) Amplifying Relay. Siemens Industry, Inc. Page 3...
- Page 4 Output pressure will equal the lower of the two input signals. Internal relief valve prevents Transfer Relay signal lock up when pressure at S-port drops below relay output pressure (maximum differential within 1.0 psi) (Figure 4). Figure 4. Lower Pressure Transfer Relay. Page 4 Siemens Industry, Inc.
- Page 5 Air supply to S-port can be from EP valve or equivalent to provide interlock with system operation (Figure 6). Figure 6. Minimum Pressure Relay. Siemens Industry, Inc. Page 5...
- Page 6 Maximum relay output can be adjusted with spring S-1. An air pressure signal from the limiting device will reduce the possible output pressure an equal amount below the maximum setting (Figure 8). Figure 8. Reverse Acting (RA) Limit Control. Page 6 Siemens Industry, Inc.
- Page 7 Initial input from controller will increase relay output above minimum at a 2/1 ratio until Pressure Relay relay output is twice the minimum value. A further increase in input pressure will increase the output an equal amount (1/1 ratio) (Figure 10). Figure 10. Characterized Min. Pressure Relay. Siemens Industry, Inc. Page 7...
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Page 8: Installation
Information in this publication is based on current specifications. The company reserves the right to make changes in specifications and models as design improvements are introduced. POWERS is a registered trademark of Siemens Industry, Inc. Other product or company names mentioned herein may be the trademarks of their respective owners.