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Siemens 5SU1644-2RC32 — Residual Current Breakers (RCCB/RCBO)

Siemens 5SU1644-2RC32 RCBO 32 A 4-pole D curve 300 mA

MPN5SU1644-2RC32

Siemens 5SU1644-2RC32 RCBO, 32 A, 4-pole, 8 modules, D characteristic, Type AC, 300 mA residual current.

Source DocumentedChannel stated on listing & quote
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Worldwide DispatchDHL/FedEx — transit quoted per order
Independent China distributor & sourcing agent· Listing updated Sep 2026

Product details

It occupies 8 module widths on a DIN rail, which is the standard 144 mm — a factor to check against enclosure fill limits when retrofitting into an existing panel.

The 32 A rating governs the thermal overload element; continuous load should not exceed 32 A, and the D curve's magnetic threshold (320–640 A instantaneous) clears hard faults without coordination issues downstream. Type AC residual current detection handles sinusoidal AC earth faults only. For variable-speed drives, UPS outputs, or LED lighting with rectifiers, a Type A or Type F RCD would be required — Type AC will not reliably detect the fault waveforms those loads generate. The 300 mA residual sensitivity is a fire-protection level, not personnel protection (30 mA is the threshold for direct contact). This unit is intended for sub-distribution or feeder circuits where the earth leakage is expected to be higher than 30 mA but still needs ground-fault detection to prevent cable overheating and fire risk.

Snap-on DIN rail mounting per EN 60715. At 8 modules (144 mm), it occupies a full row on a standard 12-module distribution board. Verify the busbar comb arrangement — 4-pole RCBOs require a 4-conductor busbar with the neutral pole switched. The neutral pole is on the right-hand side (phase sequence L1-L2-L3-N).

This RCBO combines overcurrent protection (MCB function) and residual current protection (RCD function) in a single 4-pole device, saving one module width compared to separate MCB + RCD units. The 32 A D curve with 300 mA Type AC residual covers the common specification for motor feeder circuits in commercial and light industrial sub-distribution boards where earth leakage is monitored for fire prevention rather than personnel shock protection.

Frequently asked questions

What is the 5SU1644-2RC32 used for?

It is a 4-pole RCBO rated 32 A with a D tripping characteristic and 300 mA Type AC residual current detection, used for combined overcurrent and earth-fault protection in motor circuits, transformers, and other high-inrush loads in sub-distribution boards.

Where can I buy the 5SU1644-2RC32?

This part is sourced and quoted to order against an RFQ through independent distribution. Availability and current pricing are confirmed at quote time.

What does D characteristic mean on this RCBO?

The D characteristic means the magnetic trip operates at 10–20 times the rated current (320–640 A instantaneous for this 32 A unit), designed to avoid nuisance tripping from high inrush currents typical of motors and transformers.

What is the difference between Type AC and Type A RCD?

Type AC detects sinusoidal AC residual currents only. Type A additionally detects pulsating DC residual currents. For circuits with VFDs, UPS, or LED drivers, Type A or Type F is required; Type AC is suitable for general resistive and inductive loads without rectified waveforms.

MPN
5SU1644-2RC32