Authorized Littelfuse Distributor
Littelfuse ALT-115-X-SW - The ALT 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 crossconnected 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!

Littelfuse ALT-115-X-SW The ALT alternating relays are used to alternate between two loads. The ALT is commonly…

Alternate Item Number: ALT115-X-SW

UPC: 079458991338

Documents & Media
BrochureSpecification SheetUser Manual

Contact for Pricing

Call +1 (262) 252-1600 (toll-free 877-268-3700) or email [email protected] for pricing and availability.

Overview

The Littelfuse ALT-115-X-SW is an 8-pin plug-in alternating relay designed for duplex pumping applications requiring balanced load alternation and manual control. This model integrates an internal cross-connected relay (ALT-X) to enable simultaneous pump operation when both lead and lag floats are closed, while maintaining alternating runtime under normal conditions. The built-in manual override switch (SW option) forces one pump to run on demand—ideal for maintenance, testing, or forced operation scenarios. A debounce circuit prevents false state changes from float switch bounce, ensuring reliable performance. The relay is housed in a compact 8-pin plug-in design, making it suitable for space-constrained control panels. Typical applications include wastewater management, sump pumping, and irrigation systems where pump runtime balancing extends equipment life and prevents uneven wear. The debounce feature ensures stable operation even in environments with vibration or electrical noise. The manual override switch allows technicians to bypass the alternating logic for testing or maintenance without disconnecting wiring. The cross-connected relay configuration in the ALT-X variant ensures both pumps can operate simultaneously when required, improving system flexibility. The ALT-115-X-SW is part of Littelfuse's Protection Relays series, a trusted brand in industrial control solutions.
  • 8-pin plug-in design for easy installation and replacement
  • Internal cross-connected relay (ALT-X) enables simultaneous pump operation when both floats are closed
  • Built-in manual override switch (SW option) for forced pump operation during maintenance or testing
  • Debounce circuit prevents false state changes from float switch bounce
  • Designed for duplex pumping applications in wastewater, sump, and irrigation systems

Specifications

Brand Name
Littelfuse
Connection Type
Socket (OT08PC)
Mounting
DIN rail or Surface mount (plug into OT08-PC socket)
Mounting Type
Socket (OT08PC)
Number Of Poles
DIN rail or surface mount (plug into OT08-PC socket)
Operating Temperature
-40 to 158
Operating Temperature, Maximum
158
Operating Temperature, Minimum
-40
Pickup Voltage
95-125 V
Poles
2P
Series
ALT
Series
ALT Series
Special Features
5YR WARR
Standard
UL/CSA
Sub Brand
Symcom
Voltage Rating
115 VAC
Package Dimensions (L x W x H)
4.13 IN x 2.38 IN x 1.75 IN
Package Dimensions (L x W x H)
104.8 mm x 60.3 mm x 44.5 mm
The ALT 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 crossconnected 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!

ALT-115-S-SW

The ALT 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 crossconnected 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!
The ALT 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 crossconnected 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!

ALT-230-S

The ALT 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 crossconnected 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!
PC-200-LLC-GM is a liquid level control relay with an input voltage ac of 190–240 and an adjustable probe sensitivity from 4.7–100 kΩ.

PC-200-LLC-GM

PC-200-LLC-GM is a liquid level control relay with an input voltage ac of 190–240 and an adjustable probe sensitivity from 4.7–100 kΩ.
130-156MD/SPP6 115-288V

HHS-6

130-156MD/SPP6 115-288V
43-55MD/SPP5 115-288V

HHS-5

43-55MD/SPP5 115-288V
145-174MD/810 125V

HHS-810

145-174MD/810 125V
243-292MD/410 125V

HHS-410

243-292MD/410 125V
The ARP Series is used in systems where equal run time for two motors is desirable. The selector switch allows selection of alternation of either load for continuous operation. LED’s indicate the status of the output relay. This versatile series may be front panel mounted (BZ1 accessory required) or 35 mm DIN rail mounted with an accessory socket. Operation: Alternating: When the rotary switch is in the “alternate” position, alternating operation of Load A and Load B occurs upon the opening of the control switch S1. To terminate alternating operation and cause only the selected load to operate, rotate the switch to position “A” to lock Load A or position “B” to lock Load B. The LEDs indicate the status of the internal relay and which load is selected to operate. Note: Input voltage must be applied at all times for proper alternation. The use of a solid-state control switch for S1 may not initiate alternation correctly. S1 voltage must be from the same supply as the unit’s input voltage (see connection diagrams on datasheet). Loss of input voltage resets the unit; Load A becomes the lead load for the next operation. Duplexing (Cross Wired): Duplexing models operate the same as alternating relays and when both the Control (S1) and Lag Load (S2) Switches are closed, Load A and Load B energize simultaneously. The DPDT 8-pin, cross-wired option, allows extra system load capacity through simultaneous operation of both motors when needed. Relay contacts are not isolated.

ARP63S

The ARP Series is used in systems where equal run time for two motors is desirable. The selector switch allows selection of alternation of either load for continuous operation. LED’s indicate the status of the output relay. This versatile series may be front panel mounted (BZ1 accessory required) or 35 mm DIN rail mounted with an accessory socket. Operation: Alternating: When the rotary switch is in the “alternate” position, alternating operation of Load A and Load B occurs upon the opening of the control switch S1. To terminate alternating operation and cause only the selected load to operate, rotate the switch to position “A” to lock Load A or position “B” to lock Load B. The LEDs indicate the status of the internal relay and which load is selected to operate. Note: Input voltage must be applied at all times for proper alternation. The use of a solid-state control switch for S1 may not initiate alternation correctly. S1 voltage must be from the same supply as the unit’s input voltage (see connection diagrams on datasheet). Loss of input voltage resets the unit; Load A becomes the lead load for the next operation. Duplexing (Cross Wired): Duplexing models operate the same as alternating relays and when both the Control (S1) and Lag Load (S2) Switches are closed, Load A and Load B energize simultaneously. The DPDT 8-pin, cross-wired option, allows extra system load capacity through simultaneous operation of both motors when needed. Relay contacts are not isolated.
The ARP Series is used in systems where equal run time for two motors is desirable. The selector switch allows selection of alternation of either load for continuous operation. LED’s indicate the status of the output relay. This versatile series may be front panel mounted (BZ1 accessory required) or 35 mm DIN rail mounted with an accessory socket. Operation: Alternating: When the rotary switch is in the “alternate” position, alternating operation of Load A and Load B occurs upon the opening of the control switch S1. To terminate alternating operation and cause only the selected load to operate, rotate the switch to position “A” to lock Load A or position “B” to lock Load B. The LEDs indicate the status of the internal relay and which load is selected to operate. Note: Input voltage must be applied at all times for proper alternation. The use of a solid-state control switch for S1 may not initiate alternation correctly. S1 voltage must be from the same supply as the unit’s input voltage (see connection diagrams on datasheet). Loss of input voltage resets the unit; Load A becomes the lead load for the next operation. Duplexing (Cross Wired): Duplexing models operate the same as alternating relays and when both the Control (S1) and Lag Load (S2) Switches are closed, Load A and Load B energize simultaneously. The DPDT 8-pin, cross-wired option, allows extra system load capacity through simultaneous operation of both motors when needed. Relay contacts are not isolated.

ARP41S

The ARP Series is used in systems where equal run time for two motors is desirable. The selector switch allows selection of alternation of either load for continuous operation. LED’s indicate the status of the output relay. This versatile series may be front panel mounted (BZ1 accessory required) or 35 mm DIN rail mounted with an accessory socket. Operation: Alternating: When the rotary switch is in the “alternate” position, alternating operation of Load A and Load B occurs upon the opening of the control switch S1. To terminate alternating operation and cause only the selected load to operate, rotate the switch to position “A” to lock Load A or position “B” to lock Load B. The LEDs indicate the status of the internal relay and which load is selected to operate. Note: Input voltage must be applied at all times for proper alternation. The use of a solid-state control switch for S1 may not initiate alternation correctly. S1 voltage must be from the same supply as the unit’s input voltage (see connection diagrams on datasheet). Loss of input voltage resets the unit; Load A becomes the lead load for the next operation. Duplexing (Cross Wired): Duplexing models operate the same as alternating relays and when both the Control (S1) and Lag Load (S2) Switches are closed, Load A and Load B energize simultaneously. The DPDT 8-pin, cross-wired option, allows extra system load capacity through simultaneous operation of both motors when needed. Relay contacts are not isolated.
189-227MD/7E 330V

HHS-7E

189-227MD/7E 330V
130-156MD/8E 330V

HHS-8E

130-156MD/8E 330V

Frequently Asked Questions

What types of fuses does Littelfuse offer for industrial applications?

Littelfuse offers UL Class fuses, high-speed fuses, medium voltage fuses, 10 x 38 mm fuses, and solar fuses for industrial applications.

What types of motor protection does Littelfuse provide?

Littelfuse offers voltage monitors, current monitors, and Bluetooth enhanced overload relays for low and medium voltage motor protection applications.

What do Littelfuse pump controllers protect against?

Pump controllers protect and disable a pump if a hazardous condition arises, with options for single-phase and three-phase applications.

What is the benefit of Littelfuse ground-fault protection relays?

Sensitive ground-fault relays with advanced filtering quickly and reliably detect insulation resistance breakdown caused by moisture, vibration, chemicals, or dust.

What does the Littelfuse trailing-cable protection relay monitor?

Trailing-cable protection relays continuously monitor the integrity of the ground conductor in portable cables to protect equipment from hazardous voltages.

What are Littelfuse fuse blocks and holders designed for?

Littelfuse fuse blocks and holders are selected by OEMs and designers for their compact designs, indication features, and DIN-rail mounting flexibility.

What do POWR-BLOKS power distribution blocks provide?

POWR-BLOKS power distribution blocks offer a safe and convenient way to splice cables and manage power distribution requirements within panels and systems.

What is the purpose of Littelfuse feeder protection relays?

Feeder protection relays protect circuits from overcurrent, ground faults, phase loss, overload, and other detrimental conditions.

What is the Industrial Shock-Block® GFCI designed for?

The Industrial Shock-Block® GFCI is designed for people protection in industrial facilities and meets UL Standard 943C Class C and Class D.

How do high-resistance grounding systems benefit industrial applications?

High-resistance grounding limits point-of-fault damage and eliminates arc-flash hazards and transit overvoltages associated with ground faults.

Frequently Asked Questions about Littelfuse

What certifications and standards do Littelfuse products comply with?

Littelfuse products are certified to multiple international standards, including UL (Underwriters Laboratories), CSA (Canadian Standards Association), CCC (China Compulsory Certification), and EAC (Eurasian Conformity). Customers can verify specific product certifications by consulting individual product datasheets on Littelfuse.com, which provide comprehensive details about standards compliance for each component.

What industries and applications are Littelfuse products used for?

Littelfuse products are critical for electrical protection and safety across multiple industrial sectors, including manufacturing, automation, power distribution, and electrical control systems. Their comprehensive product portfolio serves industries that require robust electrical protection, including motor and pump applications, solar installations, programmable logic controllers (PLCs), electrical switch panels, and critical infrastructure environments. Key product lines protect against overcurrent, voltage transients, ground faults, and temperature-related electrical risks, ensuring equipment safety and operational reliability.

What technical support does Littelfuse offer?

Littelfuse offers comprehensive technical support through multiple channels. Their Technical Hotline (800-TEC-FUSE) provides direct access to engineers who can help identify issues and recommend solutions. Additionally, Littelfuse offers extensive online Technical Resources at Littelfuse.com, including datasheets, product manuals, whitepapers, application guides, and online design tools. Their experienced product and application engineers also provide step-by-step support from design to installation.

What are the main product lines offered by Littelfuse?

Littelfuse offers comprehensive industrial protection and control product lines, including fuses, fuse holders, protection relays, temperature sensors, and electrical safety components. Their key product categories span surge protective devices, custom OEM products, electrical switch panels, medium voltage fuses, ground-fault protection relays, motor and pump protection devices, and temperature sensors. These products are designed to minimize electrical safety hazards, limit equipment damage, improve productivity, and safeguard personnel from electrical faults.

What are the key features of Littelfuse products?

Littelfuse products feature exceptional circuit protection technologies with key characteristics including UL/IEC safety standard compliance, low internal resistance, and advanced protective capabilities across multiple product lines. Their components provide critical protection for industrial systems, offering features like overcurrent protection, voltage transient suppression, and resettable protection devices with ultra-low resistance and compact designs. Key product lines include fuses, metal oxide varistors (MOVs), TVS diodes, PolySwitch devices, and specialized electronic protection components that enhance system reliability and safety.

What environmental ratings do Littelfuse products have?

Littelfuse products feature comprehensive environmental ratings, including NEMA Type 1, 2, 3, 3R, 4/4X, 12, and 13 certifications, as well as IP65 protection. These ratings ensure superior protection in diverse industrial environments, with an operating temperature range of -40°F to +131°F (-40°C to +55°C). Many products also include UV-stabilized materials and neoprene gaskets for enhanced durability in outdoor and challenging conditions.

What accessories are available for Littelfuse products?

Littelfuse offers several key accessories across their product lines, including fuse holders, voltage monitoring modules, and terminal connectors. Specific accessories include the LPSM003ZXID (indicating) and LPSM003Z (non-indicating) POWR-SAFE Dead Front fuse holders for Class CC and Midget-Style fuses, the VRM6048 voltage monitor accessory module, and female quick connect terminals (P1015 series) in various wire gauge sizes. These accessories are designed to enhance protection, monitoring, and connectivity for Littelfuse electrical components.

What is Littelfuse's warranty policy?

Littelfuse provides comprehensive warranty details on their official website at www.littelfuse.com/warranty. Customers should visit this page to review the specific warranty terms and conditions for their specific product lines. For direct warranty support or questions, customers can contact Littelfuse Technical Support at 1-800-TEC-FUSE or email [email protected].

What communication protocols do Littelfuse products support?

Littelfuse supports a comprehensive range of industrial communication protocols, including PROFIBUS, PROFINET, EtherNet/IP, DeviceNet, Modbus RTU, and CANopen. Our products provide flexible connectivity solutions across multiple industrial automation platforms, enabling seamless integration with various control systems and network architectures.

How are Littelfuse products typically installed?

Littelfuse products are typically installed using specialized mounting hardware like fuse holders, blocks, and panels designed for specific industrial applications. The POWR-SAFE Dead Front holders, for example, provide optimum protection for Class CC and Midget-Style fuses, supporting installations up to 600 VAC/DC. Installation often involves using precision terminals with strain relief, such as 0.25 in. female quick connect terminals, to ensure secure and safe electrical connections in industrial control systems.