Siemens N12SNDA Neutral Transformer Unit

Module Feature

N12SNDA is Siemens Sentron series neutral sensing current transformer, rated 1200A. It is installed on neutral conductor of distribution circuit, detects neutral residual current and sends signal to ground fault protection trip unit. It supports matching Sentron molded case circuit breaker, widely used in low‑voltage power distribution cabinets.

Working principle

When earth leakage fault occurs, residual current flows through neutral line. The transformer induces corresponding secondary current signal, which is transmitted to protection module to judge ground fault and trigger breaker tripping.

Onboard components

Iron core, secondary winding, signal output terminals, insulating housing.

LED indicators

No onboard LED indicators. No power indication, passive sensing component.

Hardware self‑diagnosis

Check secondary winding continuity, inspect insulation resistance, verify wiring tightness and avoid open circuit on secondary side.

Programming software

No configuration software, passive current sensing component.

Electrical & Process Parameters

Model:N12SNDA Brand:Siemens Device type:Neutral Sensing Current Transformer Rated primary:1200A Function:Residual current detection for ground fault protection

Mechanical & Structure

Mounting:Panel / busbar mounting Protection class:IP00 Housing:Insulated plastic housing

Environmental

Operating temperature:-20℃ ~ +60℃ Storage temperature:-40℃ ~ +85℃ Ambient humidity:5~95% non‑condensing Certification:CE, UL, IEC61869 compliant Status: Siemens Sentron original neutral CT

Installation

Pass neutral busbar through CT window. Connect secondary signal wires to breaker ground‑fault trip unit. Strictly prevent secondary side open circuit during operation.

Interface

Secondary signal output terminals, busbar through window.

Diagnostic

Ground fault protection failure: secondary wire break or wrong wiring. Incorrect leakage reading: installation offset or nearby strong magnetic interference.

Product Brief

Siemens N12SNDA 1200A neutral sensing transformer, provides residual current signal for Sentron MCCB earth fault protection.