Littelfuse 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!
Littelfuse

ALT-115-S-SW

Alternate Item Number: ALT115-S-SW

UPC: 079458991314

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Overview

The Littelfuse ALT-115-S-SW alternating relay is a critical component for ensuring the reliable and efficient operation of duplex pumping systems. Designed to distribute workload evenly between two pumps, this relay significantly extends the lifespan of each unit by preventing one pump from being overused. This is particularly vital in applications such as wastewater management, sump pumping, and water supply systems where continuous operation is paramount. The primary function of the ALT-115-S-SW is to alternate the operation of two connected loads. In a typical duplex pumping setup, when the primary pump reaches its operational limit (e.g., a high-level float switch opens), the Littelfuse ALT relay switches the active load, forcing the second pump to engage. This ensures that both pumps share the runtime equally, preventing premature wear and tear on a single unit and reducing the likelihood of unexpected failures. This intelligent load balancing is a cornerstone of preventative maintenance in critical fluid handling systems. A key feature of all Littelfuse ALT relays, including the ALT-115-S-SW, is the integrated debounce circuit. This advanced functionality is designed to counteract the effects of contact bounce, a common phenomenon in mechanical switches and float mechanisms. Contact bounce occurs when electrical contacts momentarily make and break multiple times upon closing or opening. The debounce feature ensures that the relay only registers a single, stable state change, thereby preventing erratic switching and potential damage to the connected pumps or control circuitry. This reliability is essential for industrial environments where consistent performance is non-negotiable. The 'SW' option on the ALT-115-S-SW model introduces a valuable manual override switch. This built-in switch allows operators to manually force one of the pumps to run, regardless of the float switch status. This capability is incredibly useful during pump maintenance, repair, or for diagnostic testing purposes. For instance, if one pump needs to be removed for servicing, the manual switch can be engaged to ensure the remaining pump continues to operate, maintaining system functionality. In the case of the ALT-X-SW variant, this switch effectively designates a lead pump while still allowing for simultaneous operation when both lead and lag floats are closed, offering enhanced control in more complex dual-float scenarios. For applications requiring UL compliance, it is imperative to use the OT08PC socket with the ALT-115-S-SW relay. Littelfuse is a globally recognized leader in circuit protection and switching solutions, renowned for its commitment to quality, innovation, and reliability. Their industrial relays are engineered to withstand demanding environments and deliver consistent performance, making them a trusted choice for professionals in the electrical and automation industries. The ALT-115-S-SW is an excellent solution for single high-level float applications where balanced pump runtime and operational flexibility are required.
  • Alternates operation between two pumps for balanced runtime
  • Built-in debounce feature prevents false switching from contact bounce
  • Manual override switch (SW option) for pump maintenance and testing
  • Ideal for single high-level float duplex pumping applications
  • Requires OT08PC socket for UL rating compliance

Specifications

Brand Name
Littelfuse
Connection Type
Screw Terminal (with OT08PC socket for UL Rating)
Mounting
DIN rail or Surface mount (plug into OT08-PC socket)
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
Series
ALT
Special Features
5YR WARR
Standard
UL/CSA
Sub Brand
Symcom
Voltage Rating
115 V
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
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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.