11
RELAY WIRING
Model 91S/92S units have a number of different relay wiring
options. The table below lists relay contact positions for all
possible combinations of power failure, state of the trans-
ducer gap and failsafe switch position. Each user must
decide, from consideration of the overall system, which
combinations of the above constitutes failsafe and alarm
conditions; and, select the appropriate relay wiring and fail-
safe positions.
*
Failsafe jumper on amplifier should be kept in low position if it
is a relay 91S.
POWER SUPPLY BOARD USER SELECTIONS
Failsafe
Failsafe
Sensor
Jumper
Jumper
Alarm
Malfunction
Gap
on
on Power
Relay
Relay
Condition Amplifier*
Supply*
(P2)
(P1)
Wet
L
L
Energized
Energized
Dry
L
L
De-Energized
Energized
Malfunction
L
L
De-Energized
De-Energized
Wet
H
H
De-Energized
Energized
Dry
H
H
Energized
Energized
Malfunction
H
H
De-Energized
De-Energized
Relay Wiring Chart—91S only
Designation
Function
Action
Allows energized state of
High (H) or
alarm relay to set for wet or
P1
Low (L) level
dry condition.
failsafe
H = de-energized when wet
L = de-energized when dry
J = alarm relay will always
de-energize with a malfunction.
Joint (J) or
I = with a malfunction &
P2*
Independent (I)
failsafe jumper (P1) in
Malfunction
(H) position, alarm relay will
energize (or remain energized
if sensor was dry when
malfunction was detected)
Selector switch definitions on power supply
board—91S only
*
The malfunction relay always de-energizes on a fault detection.
AMPLIFIER BOARD
USER SELECTION DESIGNATIONS
WET LED (LED1)
An LED which illuminates red when liquid fills the sensor tip
or gap.
DRY LED (LED2)
An LED which illuminates green when air is in the sensor tip
or gap.
Time Delay Potentiometer (R31)
The adjustable time delay (R31) can be variable from 0.5 to
30 seconds. This can be used under turbulent conditions to
reduce relay chattering.
High/Low Level Failsafe (P2 Jumper)
The term failsafe denotes the position the relay contacts
assume when power to the unit is lost. To set a high level
failsafe (relay energized dry), place jumper between middle
pin and (HIGH) pin on P2. To set low level failsafe (relay ener-
gized wet), place jumper between middle pin and (LOW) pin.
Time Delay on Rising and/or Falling Jumper (P1)
The jumper (P1) can be set to delay on rising or to delay
falling level. Setting in the (RISING) position adjusts the
delay on a dry to wet transition with a fixed 0.5 second
delay on a wet to dry transition. Set in the (FALLING) posi-
tion adjusts the delay on a wet to dry transition with a fixed
0.5 second delay on a dry to wet transition. Totally removing
jumper provides delay on rising and falling level.
Auto Fill/Auto Empty Selection (P1–Dual point)
A jumper which allows the selection of an automatic fill or
automatic empty function.
Control–Malfunction Relay Action (P2–Dual point)
A jumper which allows joint or independent actuation of the
control and malfunction relay. Independent (IND) allows
separate action of each relay while joint (JOINT) ties the
control with malfunction together if either changes state.
Top Point Relay LED (DS2)
An LED on the 92S power supply board which illuminates
red when control relay tied to top point changes state.
Bottom Point Relay LED (DS3)
An LED on the 92S power supply board which illuminates
red when the control relay tied to the bottom point ener-
gizes.
Malfunction Relay LED (91S–DS2, 92S–DS1)
An LED on the power supply illuminates red when the mal-
function relay is energized, indicating a normal condition. In
case of a failure, light will go off.
Control Function Switch (92S–S2)
A three position switch which allows the user to select the
control function of the dual point unit. Select from simple
B o t t o m P o i n t – T o p P o i n t o p e r a t i o n , C o n t r o l
Function–Bottom Point, or Control Function–Top Point.
TIME DELAY
All Model 91S/92S units are provided with an adjustable
time delay of approximately 0.5 to 30 seconds. The time
delay potentiometer is on the upper right corner of the
amplifier PC board and marked TIME DELAY. There is a
jumper selector marked P1 on the amplifier board. This is
the wet and/or dry time delay. The time delay can be made
on rising and/or falling level. When the jumper is placed in
the (RISING) position, there will be an adjustable delay on a
dry to wet transition, with a fixed 0.5 second delay on wet
to dry transition. When the jumper is set in the (FALLING)
position, the delay will be on a wet to dry transition with a
fixed delay of 0.5 seconds on a dry to wet transition. If no
jumper is placed on the pins, the delay will be in both direc-
tions. Minimum time delay occurs with potentiometer
adjustment fully counterclockwise. Increase time delay by
turning clockwise. Refer to Figure 9 on page 8.
POWER SUPPLY BOARD
USER SELECTION DESIGNATIONS
