In the field of industrial power distribution and equipment protection, voltage drops or power outages may cause unexpected shutdowns of production lines, equipment damage, and even safety accidents. Eaton's Time Delay Undervoltage Module is designed specifically for use with various types of circuit breakers. By introducing an adjustable delay trip function, it effectively avoids false tripping caused by instantaneous voltage fluctuations and improves the reliability and continuity of the system. This article is based on the official technical manual (IL5721B33H03), providing a comprehensive analysis of the module's functional principles, technical specifications, installation wiring, and safety standards.
Product Overview: Function and Scope of Application
The delay undervoltage module is a remotely installed auxiliary device, whose main function is to provide controllable delay protection for the undervoltage release (UVR) of the circuit breaker. When a drop or loss of input voltage is detected, the module will not immediately trigger the trip, but will temporarily supply power to the trip breaker using internal energy storage capacitors. The delay time can be set by the user, up to a maximum of 2 seconds. This design effectively prevents unplanned shutdowns caused by transient fluctuations in the power grid or short-term voltage dips.
This module is applicable to various circuit breaker series under Eaton, including:
Air circuit breakers: Magnum DS, Magnum, Power Defense ICCB, Series NRX, IZM26, IZM9, IZMX
Molded Case Circuit Breakers: Select Molded Case Circuit Breakers
The module complies with UL, CSA, and IEC standards and has passed CE certification, meeting the safety and electromagnetic compatibility requirements of the international market.
Working principle and technical characteristics
The internal structure of the module is simple and efficient: the input AC voltage is rectified by a diode bridge and converted into DC output, which is supplied to the undervoltage release on the circuit breaker. At normal voltage, the green LED indicator light (Power On) lights up, indicating that the module is working properly. When the voltage drops below the set threshold or is completely lost, the module immediately activates the energy storage capacitor to provide temporary voltage to the release, and the duration is determined by the delay set by the user (0.1 seconds to 2.0 seconds). If the voltage returns to normal during the delay period, the release will not operate, thus avoiding false tripping.
Key features:
Adjustable delay: Select 0.1 seconds, 0.5 seconds, 1.0 seconds, or 2.0 seconds through jumper, with a factory default value of 0.1 seconds. If there is no jumper installation, the default time is also 0.1 seconds.
Voltage specifications:
120 V AC model: suitable for undervoltage release of 110-127 V AC
230 V AC model: suitable for undervoltage release of 208-240 V AC
Power frequency: 50/60 Hz universal

LED status indicator: Green LED indicates normal power supply
Surge immunity: compliant with IEC 61000-4-5 standard, ensuring reliable operation in industrial environments
Installation Guide: DIN Rail Installation and Disassembly
The module adopts DIN rail installation method, which is easy to integrate into the distribution cabinet. Its external dimensions are shown in Figure 2 (metric units in parentheses). The installation steps are as follows:
Hang the hook above the module on the upper edge of the guide rail.
Press down firmly on the bottom of the module to secure it into the lower edge of the guide rail. The initial installation may require moderate force.
When disassembling, use a screwdriver to insert into the foot slots on both sides of the bottom of the module, and pry the plastic shell to detach it from the guide rail.
Attention: The left terminal of the J2 connector of the module is positive, but due to the presence of a full wave bridge rectifier circuit inside the undervoltage release of the circuit breaker, users do not need to worry about polarity when wiring.
Wiring instructions and external controls
The wiring diagram is shown in Figure 3, and the overall scheme is "input into the module, output to the undervoltage release". For Magnum, IZM, or Mini Vac circuit breakers, they need to be connected to auxiliary contacts A-7 and A-8. The wire requirements are as follows:
Wire specifications: Copper wire only, # 14 AWG (1.63 mm ²) or # 16 AWG (1.22 mm ²)
Temperature rating: 75 ° C
Optional external emergency stop button:
As shown in the alternative wiring scheme in Figure 3, users can connect a normally closed button in series in the circuit connected to the undervoltage release. When this button is pressed, it can immediately trigger the undervoltage trip without any delay, achieving the emergency stop function. The contact rating of this button needs to meet: 3 A @ 250 V DC.
Connector information:
Module to voltage detection terminal connector: part number 1835122 (5-pin Phoenix plug-in connector)
Undervoltage release to module connector: part number 1835106
Safety Warning and Operating Standards
The installation and maintenance of modules must be operated by qualified electrical personnel and strictly comply with the following safety rules:
Power off operation: Before contacting the equipment, the power supply of the main circuit and control circuit must be disconnected.
Circuit breaker position: Drawer type circuit breakers should be shaken out to the isolation position.
Spring energy storage release: All circuit breakers should be placed in the "OFF" position and release the mechanism spring.
Prevent accidental restart: Ensure that the device cannot be unexpectedly powered on again.
Isolation verification: Confirm complete isolation from the power supply, and if necessary, perform grounding and short circuiting.
Protection of adjacent live parts: Cover or set up barriers for adjacent live parts.
Warning: Failure to follow the above steps may result in death, personal injury, or property damage.
Summary of Technical Specifications
Parameters: 120 V AC model, 230 V AC model
Input voltage 110-127 V AC 208-240 V AC
Under voltage release matching voltage 110-127 V AC 208-240 V AC
Delay setting 0.1/0.5/1.0/2.0 seconds 0.1/0.5/1.0/2.0 seconds
Power frequency 50/60 Hz 50/60 Hz
Installation method DIN rail DIN rail
Applicable standards include UL certification (E52096SP), CSA, IEC 61000-4-5, and CE as above
Wire requirements # 14- # 16 AWG copper wire, 75 ° C as above
Application scenarios
Industrial production line: To prevent the entire production line from shutting down due to transient voltage drops in the power grid, ensuring continuous production.
Key infrastructure, such as data centers, hospitals, and traffic control systems, to avoid false tripping and impact on critical loads.
Generator and backup power switching scenario: During the power switching process, use the delay function to smoothly transition and avoid misoperation.
Remote control and emergency stop: Emergency release is achieved through external buttons to meet safety interlock requirements.
