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Littelfuse 455-575 - 3PH Lin-Lod VltMon/475-600V/aj.VUB,TD,RD. The 455 Series are 3-phase voltage monitors that combine load and line side monitoring to offer complete protection. Monitoring the load side will alert the user of contactor failure or impending contactor failure. Line side monitoring will also protect the motor from damaging fault conditions that may be present prior to the motor starting. With other line/load side monitors, the motor must be started before a voltage fault is detected. With the 455, your motor is fully protected at all times. The 455 Series are 3-phase, dual range voltage monitors that protect 190-480VAC, 50/60Hz motors, regardless of their size. It automatically selects between the 200V and 400V rangewhen the user selects the nominal voltage setpoint. Other adjustments include a 2-30 second trip delay, a 2-300 second restart delay (and manual restart) and a voltage unbalance trip point of 2-8percent. The voltage monitor’s circuitry is powered through the line side connections, so there is no need for separate control power, making it easy to install. Equipped with an infrared LED, the 455 Series can communicate to the optional hand-held diagnostic tool, Informer-MS to obtain valuable information such as real-time voltage, voltage unbalance on both line and load sides, motor run hours, last 20 faults, last 32 motor starts, high and low voltage trip points, voltage unbalance trip.

Littelfuse 455-575 3PH Lin-Lod VltMon/475-600V/aj.VUB,TD,RD. The 455 Series are 3-phase voltage monitors…

UPC: 079458989830

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Contact for Pricing

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

Overview

The Littelfuse 455-575 (SKU: 455-575) is a 3-phase, dual-range voltage monitor engineered for industrial motor systems operating between 475-600VAC at 50/60Hz. Unlike conventional voltage monitors that only detect faults after motor startup, the 455 Series provides comprehensive protection by monitoring both line and load sides simultaneously. This dual monitoring capability alerts users to contactor failures or impending failures on the load side while detecting damaging voltage faults on the line side before motor activation. The device automatically selects between the 200V and 400V ranges based on the user-selected nominal voltage setpoint, eliminating manual range configuration. Key protection features include adjustable trip delays (2-30 seconds), restart delays (2-300 seconds with manual restart option), and voltage unbalance trip points (2-8%). The 455 Series operates without requiring separate control power, as it is powered through line side connections, simplifying installation and reducing wiring complexity. For advanced diagnostics, the monitor features an infrared LED compatible with the optional Informer-MS handheld tool, enabling real-time voltage monitoring, fault history review (last 20 faults), motor run hour tracking, and analysis of the last 32 motor starts. The device also provides visibility into high and low voltage trip points and voltage unbalance conditions on both line and load sides. Ideal for protecting motors in industrial applications such as pumps, conveyors, HVAC systems, and manufacturing equipment, the 455-575 ensures continuous electrical system reliability by preventing costly damage from undervoltage, overvoltage, phase loss, or voltage unbalance conditions.
  • Dual line/load side voltage monitoring for complete motor protection
  • Automatic range selection between 200V and 400V based on setpoint
  • Adjustable trip delays (2-30 sec) and restart delays (2-300 sec)
  • Voltage unbalance trip point adjustable from 2-8%
  • Infrared LED for diagnostics with optional Informer-MS handheld tool

Specifications

Brand Name
Littelfuse
Connection Type
Screw Terminal
Frequency
50/60 Hz
Mounting Type
DIN Rail / Surface Mount
Operating Temperature
-40 to 158
Operating Temperature, Maximum
158
Operating Temperature, Minimum
-40
Poles
3-Phase
Poles
3P
Series
455 Series
Series
455
Special Features
5YR WARR
Standard
UL/CSA/CE
Sub Brand
Symcom
Voltage Rating
190-480 VAC
Voltage Rating
475-600 V
The 777-LR-P2 three-phase current and voltage monitor provides motor protection with input voltage from 200–480 V ac and motor full load ampere range of 1–9 A (direct); 10–800 A (external CTs required).

777-LR-P2

The 777-LR-P2 three-phase current and voltage monitor provides motor protection with input voltage from 200–480 V ac and motor full load ampere range of 1–9 A (direct); 10–800 A (external CTs required).
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
CM-PFE.2 PHASE SEQ. MONITORING REL.

1SVR550826R9100

CM-PFE.2 PHASE SEQ. MONITORING REL.
Relay 460V 3 Phase Monitor

18883000015

Relay 460V 3 Phase Monitor
3PH VOLT mntr/190-240V/adj.restart Dly. The 350 is a heavy-duty voltage monitor. This product should be used when high current relays or dual contacts are required, or 480V controls are used. Since the 350 uses heavy-duty relays, it comes in fixed voltage range models rather than a dual autoranging version like the Model 250. The 350-200 has a 15A general purpose contact. The 350-400 provides a SPDT (Form C) relay rated to switch up to 600V, allowing the use of 480V controls, eliminating the need for a control power transformer to step the voltage down to 120-240V. Several DPDT (two Form C contacts) relay models are also available. The 350 microcontroller-based family of products are low cost yet highly advanced solutions to heavy-duty problems. The 350 includes advanced single LED diagnostics. Five different light patterns distinguish faults and normal operating conditions. Other options such as high voltage trip and adjustable restart delay are available.

350-200-2

3PH VOLT mntr/190-240V/adj.restart Dly. The 350 is a heavy-duty voltage monitor. This product should be used when high current relays or dual contacts are required, or 480V controls are used. Since the 350 uses heavy-duty relays, it comes in fixed voltage range models rather than a dual autoranging version like the Model 250. The 350-200 has a 15A general purpose contact. The 350-400 provides a SPDT (Form C) relay rated to switch up to 600V, allowing the use of 480V controls, eliminating the need for a control power transformer to step the voltage down to 120-240V. Several DPDT (two Form C contacts) relay models are also available. The 350 microcontroller-based family of products are low cost yet highly advanced solutions to heavy-duty problems. The 350 includes advanced single LED diagnostics. Five different light patterns distinguish faults and normal operating conditions. Other options such as high voltage trip and adjustable restart delay are available.
The 777-KW/HP-P2 three-phase current and voltage monitor provides protection with input voltage from 200–480 V ac and motor full load ampere range as follows: 2–20 A (looped conductors required); 20–90 A direct; 90–800 A (external CTs required).

777-KW/HP-P2

The 777-KW/HP-P2 three-phase current and voltage monitor provides protection with input voltage from 200–480 V ac and motor full load ampere range as follows: 2–20 A (looped conductors required); 20–90 A direct; 90–800 A (external CTs required).
The 777-P2 three-phase current and voltage monitor provides motor protection with input voltage from 200–480 V ac and motor full load ampere range as follows: 2–20 A (looped conductors required): 20–90 A (direct); 90–800 A (external CTs required).

777-P2

The 777-P2 three-phase current and voltage monitor provides motor protection with input voltage from 200–480 V ac and motor full load ampere range as follows: 2–20 A (looped conductors required): 20–90 A (direct); 90–800 A (external CTs required).
3PH VOLT Monitor/190-240V/adj.VUB,TD,RD. The 355 is a 3-phase voltage monitor with adjustable trip and restart delay, adjustable voltage unbalance and multiple diagnostic lights. It is perfect for heavy-duty applications that need both protection and simple user-friendly diagnostics. Applications include pump panels, commercial HVAC, oil rigs and others. The 355 uses microcontroller technology to monitor incoming voltage and de-energize its output relay if power problems exist. The 355 can protect motors from damage caused by single-phasing, high and low voltage, phase reversal and voltage unbalance. It has four diagnostic LEDs that clearly show overvoltage, undervoltage, voltage unbalance, reverse-phase and normal conditions. Equipped with a heavy-duty 10A general purpose SPDT relay. A high voltage (600V) DPDT relay output option is available with the 400V model.

355-200

3PH VOLT Monitor/190-240V/adj.VUB,TD,RD. The 355 is a 3-phase voltage monitor with adjustable trip and restart delay, adjustable voltage unbalance and multiple diagnostic lights. It is perfect for heavy-duty applications that need both protection and simple user-friendly diagnostics. Applications include pump panels, commercial HVAC, oil rigs and others. The 355 uses microcontroller technology to monitor incoming voltage and de-energize its output relay if power problems exist. The 355 can protect motors from damage caused by single-phasing, high and low voltage, phase reversal and voltage unbalance. It has four diagnostic LEDs that clearly show overvoltage, undervoltage, voltage unbalance, reverse-phase and normal conditions. Equipped with a heavy-duty 10A general purpose SPDT relay. A high voltage (600V) DPDT relay output option is available with the 400V model.

Frequently Asked Questions

What voltage range does the 455-575 support?

The 455-575 supports a voltage range of 475-600VAC at 50/60Hz.

Does the 455-575 require separate control power?

No, the 455-575 is powered through line side connections, eliminating the need for separate control power.

What is the adjustable voltage unbalance trip point range?

The voltage unbalance trip point is adjustable from 2-8%.

What accessories are available for the 455-575?

The Informer-MS handheld diagnostic tool and Informer IR Kit-36 infrared adapter cable are available for diagnostics.

What is the trip delay range for the 455-575?

The trip delay is adjustable from 2-30 seconds.

What is the restart delay range for the 455-575?

The restart delay is adjustable from 2-300 seconds with manual restart option.

What is the weight of the 455-575?

The 455-575 weighs 0.94 lb (426.38 g).

What are the dimensions of the 455-575?

The dimensions are H 74.42 mm (2.93"), W 133.86 mm (5.27"), D 74.93 mm (2.95").

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.