Square D LRA36400U31X Molded Case Circuit Breaker
- 400A
- 3 Pole
- I-Line
Quantity
Square D LRA36400U31X - 400A 3 Pole Molded Case Circuit Breaker
New
Quantity
Description
Built to handle extreme fault conditions, this 400A PowerPacT L-frame breaker features a MicroLogic 3.3 LI trip unit. The microprocessor design delivers highly accurate, adjustable long-time and instantaneous settings. Utilizing the proven I-Line connection, it mounts rapidly into Square D panelboards. This model serves as a modern upgrade for legacy LI36400 breakers. Rated for an exceptional 200 kAIC at 480VAC, it provides superior current-limiting capabilities and true RMS sensing.Specifications
| Brand | Square D |
|---|---|
| Part Number | LRA36400U31X |
| Series | LRA |
| Amperage | 400A |
| Poles | 3 |
| Mounting Style | I-Line |
| Voltage | 240VAC, 480VAC, 600VAC |
| Phase | 3 |
| AIC Rating | 200kA @ 240VAC, 200kA @ 480VAC, 100kA @ 600VAC |
| Amperage Range | 125-400A |
|---|
| Frame Type | LRA |
|---|---|
| Terminal Type | Lugs |
| For Use With | Square D I-Line Panelboards, Switchboards |
| Wire Gauge | (2) 2/0 AWG-500 kcmil (Al/Cu) |
| Max Wire | 500 kcmil |
| Min Wire | 2/0 AWG |
| Trip Technology | Electronic Trip |
|---|---|
| Trip Function Code | LI |
| Trip Function | Long-Time, Instantaneous |
| Trip Adjustability | Adjustable |
| Available Options | Shunt Trip, Auxiliary Switch, Undervoltage Release, Alarm Switch, Padlock Attachment, Motor Operator |
|---|---|
| Accessories | MicroLogic 3.3 Trip Unit |
| Standards | CSA C22.2 No 5, IEC 60947-2, NEMA AB 1, UL 489 |
| Approval | CCC, CE, CSA, IEC, NEMA, NOM, UL, UKCA |
| Temp Rating | -25C to 70C |
| Construction Features | HACR Rated, Current Limiting, True RMS Sensing, 80% Rated, Reverse Feed, Visual Trip Indicator, Quick-Make/Quick-Break |
Product FAQs
8 answersWhat panelboards are compatible with the LRA36400U31X?
This PowerPacT L-Frame breaker is designed exclusively for Square D I-Line panelboards and switchboards. It utilizes a plug-in mounting bracket on the line side for rapid installation onto the bus assembly.
What does the U31X suffix indicate on this Square D breaker?
The U31X suffix specifies that the breaker is equipped with a MicroLogic 3.3 electronic trip unit. This standard trip unit provides adjustable Long-Time and Instantaneous (LI) protection settings.
Can the LRA36400U31X replace older legacy breakers?
Yes, this PowerPacT L-Frame model serves as a direct, modern upgrade for legacy Square D 400A I-Line breakers, such as the older LI36400 series, while providing advanced electronic trip capabilities.
What wire sizes are accepted by the load lugs on this 400A breaker?
The factory-installed mechanical lugs accept two conductors per phase. They are rated for 2/0 AWG to 500 kcmil aluminum or copper wire.
What does the R in the LRA36400U31X catalog number signify?
In the Square D PowerPacT nomenclature, the R designates an ultra-high interrupting capacity. This frame delivers up to 200kA at 480VAC and 100kA at 600VAC, making it suitable for systems with high available fault currents.
Does the MicroLogic 3.3 trip unit offer true RMS sensing?
Yes, the electronic trip unit utilizes true RMS sensing. This ensures accurate current measurement and reliable overcurrent protection, even in electrical systems experiencing harmonic distortion.
How is the line-side connection made on this I-Line breaker?
The breaker features a plug-in jaw assembly on the line side that snaps directly onto the I-Line panelboard bus. This eliminates the need for line-side cabling and torquing, reducing installation time.
Are the trip settings adjustable on the LRA36400U31X?
Yes, the integrated MicroLogic 3.3 trip unit features adjustable dials for both the Long-Time pickup and Instantaneous pickup. This allows panel builders to precisely coordinate the breaker with the specific load and system requirements.
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