© 2016 Littelfuse Protection Relays & Controls
Protection Relays
Pump Controls and Liquid Level Controls
www.littelfuse.com/
Rev: 1-A-062716
www.littelfuse.com/altxxx1sw-altxxx3sw
Alternating Relay
ALT-XXX-1-SW / ALT-XXX-3-SW SERIES
Wiring Diagram
Description
The ALT-xxx-1-SW/ALT-xxx-3-SW Series are used to alternate
between two loads and are commonly used in duplex
pump-up and pump-down applications to balance the runtime
of both pumps.
The ALT relays have a built-in debounce time delay that prevents
the relay from changing state if the float momentarily bounces,
and they have a built-in switch to manually force a specific load
(pump) to operate each time the input float closes. This is helpful
when performing periodic maintenance or pump repair.
Must use the OT08PC socket for the 8-pin models, and the OT11PC socket for the
11-pin models, 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 rapid cycling caused by waves or splashing
in the tank
LED indicators
Visual indication of load operation in
duplex application
Built-in manual switch
to force load operation
Helpful to control load operation when performing
periodic maintenance or pump repair
ALT-xxx-3-SW
offers duplexing
Allows lag pump to energize if lead pump can’t
handle current demand
Accessories
OT08PC 8-pin Octal Socket
Octal Socket for plug-in units. 8-pin surface &
DIN rail mountable. Rated for 10A @ 600VAC.
OT11PC 11-pin Magnal Socket
11-pin surface & DIN rail mountable. Rated for
10A @ 300VAC
TYPICAL WIRING DIAGRAM FOR ALT-XXX-1-SW
TYPICAL WIRING DIAGRAM
FOR ALT-XXX-3-SW
Ordering Information
MODEL
LINE
VOTAGE
MOUNTING DESCRIPTION
ALT-100-1-SW 95-120VAC
11-pin
magnal
Single float input, two isolated
Form C relays (DPDT), 2 LEDs
for load indication
ALT-100-3-SW 95-120VAC 8-pin octal
Three float inputs (lead, lag,
stop floats), actuating latching
relays on lead/lag floats,
2 LEDs for load indication
ALT-200-3-SW 190-240VAC 8-pin octal
Three float inputs (lead, lag,
stop floats), actuating latching
relays on lead/lag floats,
2 LEDs for load indication
