Kraus & Naimer KG251 Disconnect Switch
The Kraus & Naimer KG251 is a solid disconnect switch designed for reliable isolation of electrical circuits. It features a durable construction and provides a clear visual indication of switch position for enhanced safety. Ideal for industrial applications requiring dependable power disconnection.
- Model
- Kraus & Naimer KG251
- Calibration
- Available on request
- Price
- $110
- Status
- In stock
- RFQ ref
- KG251
This unit
The Kraus & Naimer KG251 is a disconnect switch engineered for reliable isolation of electrical circuits in industrial settings. Rated for 250 A at 690 V nominal, it accommodates both 3-pole and 4-pole configurations and handles motor loads across utilization categories AC-3 and AC-23A. The switch provides forced opening and closing of main contacts, substantial creepage and clearance distances between terminals, and terminal shrouding on models rated 80 A to 250 A for simplified field wiring.
Technical Specifications
Rated Thermal Current: 250 A (Iu/Ith and Ithe)
Rated Uninterrupted Current: 250 A
Nominal Voltage: 690 V
Rated Insulation Voltage: 600 V AC
Rated Impulse Withstand Voltage: 8 kV (Overvoltage Category III, Pollution Degree 3)
Rated Short-Time Withstand Current: 4600 A for 1 second
Maximum Fuse Rating: 250 A (gG characteristic)
Power Loss per Pole: 8 W
Poles: 3-pole and 4-pole models available
Auxiliary Contacts: Optional 2NO/2NC configurations
Rated Operational Current
AC-20A: 250 A
AC-21A: 250 A at 20–690 V
AC-22A: 200 A at 220–500 V; 125 A at 660–690 V
Motor Switching Power (AC-3 / AC-23A)
AC-3: 37 kW to 75 kW depending on voltage and phase configuration
AC-23A: 45 kW to 110 kW depending on voltage and phase configuration
Key Features
Forced contact operation for main contacts
High dimensional clearance enabling straight-line terminal wiring
Terminal shrouds supplied on 80 A–250 A models
Screw or ring terminal options with specified torque requirements (16 Nm for M12)
IP65 enclosure protection on panel-mount variants
Typical Applications
Main or maintenance isolation for machine tools
Distribution panels and switchboards
Motor load switching and starting circuits
Mixed resistive and inductive load control
Compatibility & Integration Valid for grounded common neutral termination supply systems. Ring cable lug dimensions: 25.00 mm and 34.00 mm terminals. Panel-mount configurations supported.
Specifications
| Parameter | Value |
|---|---|
| Voltage / Current Range | 250 A at 690 V nominal |
Kraus & Naimer KG251 — Repair & Calibration Service
Aumictech offers NIST-traceable calibration and repair for the Kraus & Naimer KG251. Calibration covers I/O channel accuracy per specification, analog output and input calibration to rated accuracy, and functional communication interface test (serial, Ethernet, fieldbus). All calibrations ship with a NIST-traceable certificate. Turnaround is typically 1–3 business days after receipt.
Common Kraus & Naimer KG251 faults: blown I/O fuses, failed analog modules, power supply capacitor failure. Common faults include blown I/O protection fuses, failed analog I/O modules, power supply capacitor failure, and serial or Ethernet communication port damage.
Kraus & Naimer KG251 price
This Kraus & Naimer KG251 is listed at $110. Calibration is available separately from $450. Contact us for volume pricing or if you need multiple units.
Kraus & Naimer KG251 calibration cost
NIST-traceable calibration for the Kraus & Naimer KG251 is $450 (standard — pass/fail certificate and calibration sticker) or $650 (full measured data at every test point, reference standards documented, traceability chain included). Calibration for this instrument covers I/O channel accuracy per specification, analog output and input calibration to rated accuracy, and functional communication interface test (serial, Ethernet, fieldbus). Turnaround is 1 to 3 business days after receipt. See full calibration details →
