Schneider LUA1C20 Signalling Auxiliary Contact Module for TeSys U Motor Starter

Model: LUA1C20 (often miswritten as LUCA1C20)

Series: TeSys U / TeSys Ultra motor starter signalling auxiliary contact block

Type: Plug-in snap-on auxiliary signalling contact, mounted on LUB power base, paired with LUCA/LUCB control units

Contact configuration: 2NO (1NO for OF running status + 1NO for SD fault trip signal)

Terminals: Screw clamp terminals

Terminal numbers: 17-18 (OF running status); 97-98 (SD fault trip)

Electrical Specifications

Rated insulation voltage Ui: 250V (IEC/UL/CSA)

Conventional free air thermal current Ith: 2.5A

Minimum reliable switching capacity: 17V / 5mA (ideal for PLC digital inputs)

Compliance standards: IEC 60947-5-1, CE, UL, CCC, Green Premium (RoHS/REACH compliant)

Net weight: 0.03 kg

Model Coding Explanation

LUA: Auxiliary contact accessory series for TeSys U

1: Single module unit

C: Signalling contact (OF+SD start/trip interlock)

20: 2 Normally Open (2NO)

Comparison: LUA1C11 = 1NO+1NC (OF+SD)

Compatible Components

Power base: LUB12, LUB32, etc.

Control unit: LUCA / LUCB / LUCC / LUCD (standard / advanced protection units)

Mounting: Plug directly into the dedicated slot on the power base, plug-and-play

Application

Remote collection of motor running feedback (OF) and overload/short-circuit trip alarm (SD) by PLC; widely used for motor status monitoring in DCS and control cabinets.

Cross-reference & Equivalent Models

LUA1C20: 2NO (OF NO + SD NO)

LUA1C11: 1NO+1NC (OF NO + SD NC)

Schneider does not publish separate service life data for the LUA1C module. It is mechanically coupled with the LUB power base and shares the same actuation mechanism.

1. Mechanical Service Life (LUB power base, contact actuation limit)

15 million operations (15 Mcycles) — this is the official mechanical endurance rating of the TeSys U power base. The LUA1C20 contact actuates synchronously with every motor start-stop cycle, which defines the contact’s mechanical lifetime limit.

Maximum operating frequency: 3600 cycles per hour (60 cycles per minute); prolonged operation above this frequency is not recommended.

2. Electrical Service Life (Key note: this is a low-level signalling contact, not a power contact)

This is a low-current signalling contact (Ith=2.5A, minimum switching capacity 17V/5mA). Most applications connect to PLC digital inputs (24VDC, 5~20mA).

Under low-signal conditions (24VDC, ≤10mA, non-inductive load), electrical service life approaches the mechanical life (nearly 15 million cycles).

When switching AC250V near 2.5A resistive loads, electrical life drops sharply to several hundred thousand cycles (no separate AC-load electrical life published in the datasheet).

3. Difference Between OF and SD Contacts

OF (running feedback, terminals 17-18): Actuates on every start-stop cycle; this high-frequency contact is the lifetime bottleneck.

SD (fault trip, terminals 97-98): Only actuates on protection tripping; it remains stationary during normal operation, so wear is negligible and failure due to frequent cycling almost never occurs.

4. Warranty Period

Contractual factory warranty: 18 months from production date (this is not the operational service life, only the manufacturer’s liability term).

Field Service Life Estimation

Typical fan & pump applications (dozens of start-stop cycles daily): 5~10 years of service is common.

Frequent-cycling process equipment (multiple cycles per minute): The 15-million-cycle limit will be reached quickly; regular contact resistance testing is recommended.

Typical failure symptom: Intermittent PLC signal loss and rising contact resistance (most common with low-level DC signals).

Supplementary Reminders

The LUA1C is a pluggable accessory. When contacts wear out, only the module needs replacement; the entire LUB base does not have to be changed.

Do not use this contact to drive contactor coils or other inductive loads directly; electric arcs will burn the contacts rapidly.

Installation Instruction for LUA1C20 (TeSys U Signalling Auxiliary Contact Module)

Type: Snap-on plug-and-play design, installed into the dedicated accessory slot on the LUB power base (next to the control unit). No screws required.

Compatible bases: LUB12, LUB32 and other TeSys U non-reversible power bases.

1. Mounting Position

On the front face of the LUB base, the side accessory slot (Slot B) next to the LUCA/LUCB control unit. Only one LUA1C signalling module can be fitted per base.

Distinction: LUA1C is dedicated OF+SD status signalling contact. Do not mix its slot with LUFN auxiliary contacts or LUFDH11 modules.

2. Standard Installation Steps (Can be fitted live; power-off operation is recommended for safety)
3. Preparation: Align the module latches with the base slide rail, with the terminal side facing outwards (terminals 17-18 & 97-98 facing the operator for easy wiring).
4. Alignment: Insert the rear guide ribs into the internal slide rail and push horizontally.
5. Locking: Push firmly until an audible click confirms both plastic latches are fully engaged.
6. Verification: Pull the module outward gently; if it cannot be pulled free, locking is complete. The terminal face should sit flush without tilting or warping.
7. Wiring: Use screw terminals. OF: 17-18; SD: 97-98, wired to PLC DI circuits.
8. Removal Procedure (No need to disconnect main circuit or control unit when replacing the module)
9. Locate the two release latches (small tabs) on both sides of the module.
10. Press both latches inward simultaneously with fingernails or a small flat screwdriver.
11. Pull the module straight out horizontally.
12. Critical Installation Constraints & Notes
13. Installation sequence: The module can be fitted either before or after the base is wired with main and secondary circuits, with no impact on existing wiring.
14. Reversed mounting is impossible: Forcing the module into the slot backwards will break the guide ribs and latches.
15. Mechanical interlock: The internal actuator only meshes with the base’s operating mechanism when fully inserted. Poor engagement causes loss of OF/SD signal synchronisation and intermittent feedback.
16. Terminals: Screw-clamp type (not spring terminals). Use 0.5～1.0 mm² flexible wires for 24VDC PLC signal circuits.
17. Environmental protection: No extra cover is provided for the fitted module; terminals remain exposed. Take dustproof measures in dusty cabinet environments.
18. Common Faults Caused by Improper Installation

No OF feedback after motor closure: Module not fully seated; actuator not meshed mechanically.

No SD signal after tripping: Module tilted; only one side latch engaged.

Signal drops when lightly touched: Broken latches; the LUA1C module must be replaced.

1. LUA1C Series (Primary Signalling Contact Modules | Front Slot B on TeSys U Base)

1) Current Production Models (Standard Ordering Items)

2) Discontinued Legacy Models with Replacement Options

Model Coding Rule

LUA1CXX

LUA: TeSys U auxiliary signalling contact series

1: Single module unit

C: OF+SD start/trip linked signalling contact

11 = 1NO+1NC; 20 = 2NO

1. Full List of Other Auxiliary Contacts in the Same TeSys U Series
2. LUFN (Front Main Slot, Power-Grade Auxiliary Contacts, 5A Rated)

LUFN11: 1NO+1NC

LUFN20: 2NO

LUFN02: 2NC

2. LUA8E (Side-Mounted Auxiliary Contacts)

LUA8E20: 2NO side-mounted auxiliary contact

3. Dedicated Status Contacts (Trip / Ready Position)

LUFDH11: Trip status auxiliary contact (SD)

LUFDA01: Ready-position contact

LUFDA10: Door interlock contact

4. Other Matching Accessories

LUFV2: Voltage monitoring module

LUFW10: Winding over-temperature protection module

LU9C1: Blank slot dust cover

III. Slot Allocation (Avoid Wrong Installation)

1. LUA1C11 / LUA1C20: Front Slot B (beside control unit), OF+SD mechanically linked; only one module allowed per base.
2. LUFN: Front Slot A, power-type auxiliary contacts.
3. LUA8E: Side slot on the power base for expanded contact capacity.
4. Universal Electrical Parameters for All LUA1C Models

Rated insulation voltage Ui: 250V AC/DC

Conventional thermal current Ith: 2.5A (low-level signalling only)

Minimum reliable signal level: 17V / 5mA (PLC DI compatible)

Mechanical service life: Coupled with LUB base, 15 million operations.