| CATALOG NUMBER | 281665 |
| Manufacturer | Eaton Moeller |
| Product Name | Eaton Moeller series NZM multi-function device adapter |
| Catalog Number | 281665 |
| Model Code | +NZM2-XKR4U |
| EAN | 4015082816650 |
| Product Length/Depth | 102 mm |
| Product Height | 35 mm |
| Product Width | 93 mm |
| Product Weight | 0.159 kg |
| Compliances | IEC |
| Certifications | CE marking |
Eaton 281665 NZM2-XKR4U Auxiliary Switch / Alarm Switch
Product Name
Eaton 281665 NZM2-XKR4U Auxiliary Switch / Alarm Switch for NZM2 Series Molded Case Circuit Breakers
Product Brief Introduction
The Eaton 281665 NZM2-XKR4U is an auxiliary switch and alarm switch (also known as a signal contact) designed for use with Eaton’s NZM2 series molded case circuit breakers (MCCBs). It is part of the NZM accessory system, allowing users to add remote signaling functions to the main circuit breaker. This model provides a changeover contact for circuit breaker status (ON/OFF) and a separate contact for trip indication (fault). The “U” suffix may indicate a specific contact configuration or voltage rating.
| Parameter | Specification |
|---|---|
| Manufacturer | Eaton (formerly Moeller) |
| Part Number | 281665 |
| Model Designation | NZM2-XKR4U |
| Compatibility | Eaton NZM2 series molded case circuit breakers |
| Number of Contacts | Typically 1 changeover contact (NO/NC) for status + 1 changeover contact for trip alarm |
| Contact Type | Snap-action, silver-plated |
| Rated Operational Voltage | 400 V AC / 250 V DC |
| Rated Thermal Current (Ith) | Typically 6 A |
| Mounting | Side-mounting on NZM2 breaker (left or right side) |
| Protection Class | IP20 |
| Material | Thermoplastic (UL 94 V-0) |
| Special Feature | “U” suffix may indicate specific voltage rating or configuration |
| Standards | IEC / EN 60947-5-1 |
Product Description
The Eaton 281665 NZM2-XKR4U is a specialized accessory designed to provide remote electrical signaling of the status of an NZM2 series molded case circuit breaker. The NZM2 is a high-performance MCCB used for main distribution, feeder protection, and large motor protection in industrial and commercial electrical systems, typically covering current ratings from approximately 60A to 250A. While the breaker itself provides excellent overcurrent protection, it does not inherently provide a remote electrical signal to indicate whether it is ON, OFF, or tripped. The NZM2-XKR4U auxiliary and alarm switch solves this problem by adding contacts that change state as the breaker operates.
The accessory is part of Eaton’s NZM accessory system, which includes a wide range of add-on modules such as auxiliary switches, alarm switches, undervoltage releases, shunt trips, and motor operators. The “XKR4U” designation indicates a specific combination of functions: typically, an auxiliary switch (for ON/OFF status) and an alarm switch (for trip status) combined in a single housing. The “4” may indicate the number of contacts or a specific contact configuration, and the “U” suffix may indicate a specific voltage rating, terminal type, or design revision. This model is designed specifically for the NZM2 frame size, which is a common size for many industrial applications.
The auxiliary switch function provides a contact that follows the main contacts of the circuit breaker. When the NZM2 breaker is manually switched to the ON position (using the handle), the auxiliary switch’s contact changes state (e.g., normally open closes, normally closed opens). This allows a PLC, a remote indicator light, or a control system to know that the breaker is ON. Conversely, when the breaker is switched OFF, the auxiliary switch returns to its normal state. The alarm switch function, however, is different. It is mechanically linked to the breaker’s trip mechanism, not just the handle position. If the breaker trips due to an overcurrent (overload or short circuit), the alarm switch changes state, and importantly, it remains in that state even if the breaker’s handle is still in the ON position (a typical indication of a trip condition). The alarm switch must be manually reset (by resetting the breaker) before it returns to its normal state. This distinction is critical: the auxiliary switch indicates the commanded state (handle position), while the alarm switch indicates the actual fault state (tripped).
Mechanically, the NZM2-XKR4U is constructed from a high-grade, self-extinguishing thermoplastic (UL 94 V-0). It is designed to mount directly onto the side of the NZM2 breaker, typically using clips or screws. No tools are required for basic attachment, though screw terminals will require a screwdriver for wiring. The accessory is compact, adding minimal width to the overall breaker assembly, which is important for space-saving panel layouts. The internal contacts are snap-action type, made of silver-plated material to ensure reliable switching even at low voltages and currents (e.g., 24V DC PLC signals). The terminals are screw-type, clearly marked with terminal numbers (e.g., 11, 12, 14 for the changeover contact) and are fingersafe (IP20).
The electrical ratings of the NZM2-XKR4U contacts are typically 6A at 400V AC for general use, and lower ratings for DC voltages. They are designed to switch control circuits, not power circuits. The contacts are potential-free (dry contacts), meaning they have no internal voltage source; they simply open or close a circuit. The “U” suffix may indicate that the device is rated for a specific control voltage (e.g., 24V DC, 110V AC, 230V AC) or has a specific contact material optimized for low-level switching. It is important to verify the exact specifications for the “U” variant.
In summary, the Eaton 281665 NZM2-XKR4U is an essential accessory for any application where remote monitoring of an NZM2 circuit breaker is required. It provides reliable, clear status indication (ON, OFF, TRIPPED) to a control system.
Product Advantages
The Eaton 281665 NZM2-XKR4U offers several key advantages that make it a preferred choice for system integrators and panel builders working with NZM2 breakers.
First, combined auxiliary and alarm switch in one unit is a significant advantage. Instead of buying two separate accessories (one for status, one for trip), the XKR4U provides both functions in a single, compact housing. This saves panel space, reduces wiring time, and lowers overall cost.
Second, clear differentiation between ON/OFF and TRIPPED states is a critical advantage. The auxiliary switch follows the handle (commanded state), while the alarm switch follows the trip mechanism (fault state). This allows a PLC or remote indicator to distinguish between a breaker that has been intentionally turned off and one that has tripped due to a fault. This is essential for proper diagnostics and alarm handling.
Third, reliable, low-level switching capability is a key advantage for modern control systems. The silver-plated, snap-action contacts are designed to reliably switch low-energy signals (e.g., 24V DC from a PLC input), which can be problematic for some heavy-duty contacts. This ensures accurate status reading.
Fourth, easy installation and integration with the NZM2 breaker save time. The accessory clips or screws directly onto the side of the breaker without needing special tools. The terminals are clearly marked and easily accessible for wiring.
Fifth, robust construction and compliance with IEC/EN 60947-5-1 ensure long-term reliability. The self-extinguishing housing and high-quality internal components are designed for industrial environments. Finally, as part of the comprehensive NZM accessory system, the XKR4U is fully compatible with other NZM2 add-ons (e.g., shunt trips, undervoltage releases), allowing for complete customization. The “U” suffix may also offer specific advantages for certain control voltages.
Use Scenarios
The Eaton 281665 NZM2-XKR4U is used in industrial and commercial power distribution applications where remote monitoring of an NZM2 circuit breaker is required.
Main Distribution Panels with Remote Monitoring: In a factory’s main electrical room, the main incoming breaker or large feeder breakers (NZM2) can be monitored by a building management system (BMS) or a PLC. The XKR4U provides signals indicating whether the breaker is ON, OFF, or tripped. This allows remote operators to know the status of the power supply.
Motor Control Centers (MCCs): For large motors protected by NZM2 breakers (e.g., 50kW to 100kW pumps, compressors, fans), the XKR4U allows the central control system to know the status of each motor’s circuit breaker. If a breaker trips, the system can generate an alarm, stop downstream equipment, or initiate a backup process.
Generator and Transfer Switch Panels: In standby generator systems, the NZM2 breaker on the generator output can be monitored by the transfer switch controller. The XKR4U provides the status signal needed for proper sequencing and fault indication.
Critical Process Control: In continuous processes (e.g., chemical plants, refineries, steel mills), knowing the exact state (ON, OFF, or TRIPPED) of key breakers is essential. The XKR4U provides this information to the distributed control system (DCS) or PLC.
Remote Unattended Substations: In electrical substations that are not staffed, the status of incoming and outgoing NZM2 breakers must be telemetered to a central control room. The XKR4U provides the necessary dry contacts for SCADA (Supervisory Control and Data Acquisition) systems.
FAQ
Q1: What is the difference between the auxiliary switch and the alarm switch in the NZM2-XKR4U?
A1: The auxiliary switch follows the position of the breaker handle (ON or OFF). It indicates the commanded state. The alarm switch follows the trip mechanism; it changes state only when the breaker trips due to an overcurrent, and it remains in that state until the breaker is reset. This allows you to distinguish between a breaker that is OFF and one that is TRIPPED.
Q2: What NZM2 breakers is the 281665 NZM2-XKR4U compatible with?
A2: It is designed specifically for the Eaton NZM2 series molded case circuit breakers (frame size for currents approx. 60A to 250A). It is not compatible with NZM1, NZM3, or NZM4 series without an adapter (if available).
Q3: What does the “U” suffix in NZM2-XKR4U signify?
A3: The “U” suffix may indicate a specific voltage rating, a particular contact configuration, a different terminal type, or a design revision. You should consult the product datasheet for the exact meaning of the “U” variant for this specific part number.
Q4: What are the electrical ratings of the contacts?
A4: The contacts are typically rated for 6A at 400V AC (for general use) and lower currents at DC voltages (e.g., 1A at 250V DC, 2A at 125V DC). They are designed for control circuits, not power switching. The “U” variant may have different ratings. Always consult the product datasheet.
Q5: Is the NZM2-XKR4U difficult to install?
A5: No, it is designed for easy, tool-free mounting onto the side of the NZM2 breaker. It clips or screws into place. Wiring is done via accessible screw terminals, which will require a screwdriver.
