Littelfuse PLR240A - The PLR Series provides a cost effective means of preventing 3-phase motor startup during adverse voltage conditions. Proper A-B-C sequence must occur in order for the PLR’s output contacts to energize. In addition, the relay will not energize when an undervoltage or phase loss condition is present. The PLR protects a motor against undervoltage operation. The adjustment knob sets the undervoltage trip point. Operation: The output relay is energized and the LED glows when all voltages are acceptable and the phase sequence is correct. Undervoltage must be sensed for a continuous dropout delay period before the relay de-energizes. Reset is automatic upon correction of the fault condition. The output relay will not energize if a fault condition is sensed as power is applied.
Littelfuse

PLR240A

Alternate Item Number: PLR240A

UPC: 079458998016

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Overview

The Littelfuse PLR240A (SKU: PLR240A) is a cost-effective 3-phase motor protection relay designed to prevent motor startup during adverse voltage conditions and ensure correct phase sequence. This relay continuously monitors three-phase power, energizing its output contacts only when all voltages are acceptable and the A-B-C phase sequence is correct. This feature is crucial for preventing motor damage caused by reverse rotation, which can occur if the phase sequence is incorrect. The PLR240A actively protects motors against undervoltage operation. An integrated adjustment knob allows for precise setting of the undervoltage trip point, providing tailored protection. For added reliability and to prevent nuisance tripping from transient voltage fluctuations, the relay incorporates a dropout delay period. If an undervoltage condition is detected, the relay will not de-energize until this delay period has elapsed. Furthermore, the PLR240A will not energize if a fault condition, such as undervoltage or phase loss, is present at power application, safeguarding equipment from immediate damage. The relay automatically resets once the fault condition is corrected. Visual feedback is provided by an LED indicator, which glows when voltages are acceptable and the phase sequence is correct. Installation is simplified by the industry-standard 8-pin octal plug connection, eliminating the need for specialized connectors. Key features include continuous monitoring, LED indication, and an 8-pin octal plug. The operating voltage range for the PLR240A is 190 to 270VAC. Applications for the PLR240A include manufacturing, pumping stations, HVAC systems, conveyors, machine tools, and any other 3-phase motor application where voltage stability and correct phase sequence are critical for reliable operation. Note: In average systems, a voltage unbalance of 10% or more is typically required for phase loss detection. The PLR Series may not provide protection under certain regeneration conditions during single-phasing. For superior phase loss protection in such scenarios, consider the Littelfuse PLMU Series.
  • Prevents 3-phase motor startup during undervoltage or phase loss conditions
  • Ensures correct A-B-C phase sequence to prevent reverse rotation
  • Adjustable undervoltage trip point for customized protection
  • LED indicator for quick visual status feedback
  • Industry-standard 8-pin octal plug for easy installation
  • Industry-standard 8-pin octal plug connection for easy installation

Specifications

Brand Name
Littelfuse
Connection Type
8-pin octal plug
Operating Temperature
0 to 55 F
Operating Temperature, Maximum
55 F
Operating Temperature, Minimum
0 F
Poles
3
Series
PLR
Special Features
10Y WARR
Standard
CE/UR/CSA
Sub Brand
SSAC
Voltage Rating
190/270 V
Package Dimensions (L x W x H)
1.78 IN x 2.39 IN x 3.2 IN
Package Dimensions (L x W x H)
45.2 mm x 60.7 mm x 81.3 mm
The PLR Series provides a cost effective means of preventing 3-phase motor startup during adverse voltage conditions. Proper A-B-C sequence must occur in order for the PLR’s output contacts to energize. In addition, the relay will not energize when an undervoltage or phase loss condition is present. The PLR protects a motor against undervoltage operation. The adjustment knob sets the undervoltage trip point. Operation: The output relay is energized and the LED glows when all voltages are acceptable and the phase sequence is correct. Undervoltage must be sensed for a continuous dropout delay period before the relay de-energizes. Reset is automatic upon correction of the fault condition. The output relay will not energize if a fault condition is sensed as power is applied.

PLR480A

The PLR Series provides a cost effective means of preventing 3-phase motor startup during adverse voltage conditions. Proper A-B-C sequence must occur in order for the PLR’s output contacts to energize. In addition, the relay will not energize when an undervoltage or phase loss condition is present. The PLR protects a motor against undervoltage operation. The adjustment knob sets the undervoltage trip point. Operation: The output relay is energized and the LED glows when all voltages are acceptable and the phase sequence is correct. Undervoltage must be sensed for a continuous dropout delay period before the relay de-energizes. Reset is automatic upon correction of the fault condition. The output relay will not energize if a fault condition is sensed as power is applied.
CM-PVS.81S THREE-PHASE MON.

1SVR730794R2300

CM-PVS.81S THREE-PHASE MON.
Three Phase Monitor Relay; DIN-Mount; 190-500V; 10A DPDT; Phase Loss; Reversal; Unbalance; Under/Over Voltage

PMDU

Three Phase Monitor Relay; DIN-Mount; 190-500V; 10A DPDT; Phase Loss; Reversal; Unbalance; Under/Over Voltage
Relay 460V 3 Phase Monitor

18883000015

Relay 460V 3 Phase Monitor

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.