POWERS
®
Controls
Technical Instructions
Document No. 155-042P25
RL 243-6
September 10, 2018
RL 243 MP Multi-Purpose Relay
Siemens Industry, Inc.
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. (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.
Product Number
243-0009
Operation
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:
R = (TD + (S
1
- TR) =
S
NOTE:
(S
1
- TR) cannot be less than zero,
Where:
R
is the output pressure
TD
is a direct acting input variable
S
1
is the setting of the adjustment spring
TR
is a reverse acting input variable (opposing S
1
)
