Cut Sheet

© 2019 Littelfuse, Inc.
Protection Relays
Alternating Relays
www.littelfuse.com/www.littelfuse.com/
Rev: 2-C-043019
www.littelfuse.com/alt
ALT SERIES
8-pin Plug-in Alternating Relay
Description
The ALT series alternating relays are used to alternate between
two loads. The ALT is commonly used in duplex pumping
applications to balance the runtime of both pumps.
The ALT-S is used in single high-level float applications. When
the float switch opens, the alternating relay changes state,
forcing the other pump to run the next time the float closes.
All ALT relays have a built-in debounce feature that prevents
the relay from changing state if the switch or float contact
bounces momentarily.
The ALT-X has an internal cross-connected relay and is used
in dual high-level float applications. These floats are commonly
referred to as lead and lag floats.
The pumps alternate as in the ALT-S version but the cross-
connected relay configuration allows both pumps to run
simultaneously when both the lead and lag floats are closed.
These relays are also available with a built-in switch (SW option)
that is used to manually force one of the pumps to run every
time the float switch is closed. This is helpful when a pump has
been removed for repair or for test purposes. In the case of the
ALT-X-SW, the switch essentially forces one pump to be the
lead pump, while still allowing the second to run when both
floats are closed.
Must use the OT08PC socket for UL Rating!
*Note: Manufacturer’s recommended screw terminal torque for the OT series
Octal Sockets is 12 in.-lbs.
Features & Benefits
FEATURES BENEFITS
Debounce time delay
Prevents nuisance actuating causes by waves or
spashing in the tank
Built-in manual/
auto switch
Force lead pump operation when a pump is
removed for repair or testing (on select models)
Ordering Information
MODEL LINE VOLTAGE DESCRIPTION
ALT024-S
†
20-26 V ac or V dc
For single high-level float applications
ALT024-S-SW
†
20-26 V ac or V dc
For single high-level float applications
with built in manual switch
ALT115-S
95-125 V ac
For single high-level float applications
ALT115-S-SW
95-125 V ac
For single high-level float applications
with built in manual switch
ALT115-X
95-125 V ac
For dual high-level (lead and lag) float
applications
ALT115-X-SW
95-125 V ac
For dual high-level (lead and lag) float
applications with built in manual switch
ALT230-S
195-250 V ac
For single high-level float applications
ALT230-S-SW
195-250 V ac
For single high-level float applications
with built in manual switch
ALT230-X
195-250 V ac
For dual high-level (lead and lag) float
applications
ALT230-X-SW
195-250 V ac
For dual high-level (lead and lag) float
applications with built in manual switch
TYPICAL WIRING DIAGRAM FOR THE ALT-S
Wiring Diagram
PUMP
#1
PUMP
#2
MAGNETIC CONTACTORS
F3
F1
F2
F4
F5
F6
F3 - F6:
SIZE FOR INDIVIDUAL
PUMP APPLICATION
F1 - F2:
1-2A TYPICAL SIZE
FOR CONTACTOR COILS
L1
L
2
L1
L2
L1
L
2
ALTERNATING RELAY
85
14
23
76
S1
S2
TYPICAL WIRING DIAGRAM FOR THE ALT-X (CROSS CONNECTED)
Accessories
OT08PC Octal 8-pin Socket
8-pin 35 mm DIN rail or surface mount. Rated at
10 A @ 600 V ac. Surface mounted with two #6
screws or snaps onto a 35 mm DIN rail.
†
ALT024-S and ALT024-S-SW are not UL Listed