> For the complete documentation index, see [llms.txt](https://docs.bituo-technik.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.bituo-technik.com/product-document/spm-series.md).

# SPM Series

## SPM Series — Miniature Energy Meters

Ultra-compact miniature energy meters with built-in CTs, designed to install directly above or below circuit breakers in final distribution boards — **no DIN rail space required**.

<figure><img src="https://68488808-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2FTmsWivaZjkubbVKrCezC%2Fuploads%2F3zv6ocL9sK7phWO9JurZ%2Fimgi_25_F3-1.jpg?alt=media&amp;token=3fb5a8f0-2d00-47bd-92bc-215ae39f793b" alt=""><figcaption></figcaption></figure>

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### Product Variants

SPM products are defined across **three dimensions**:

#### 1. Product Platform

<table><thead><tr><th width="141"></th><th>SPM01</th><th>SPM02</th></tr></thead><tbody><tr><td><strong>Phase</strong></td><td>Single-phase (1PN)</td><td>Three-phase (3PN)</td></tr><tr><td><strong>Rated Voltage</strong></td><td>220–240 VAC (L-N)</td><td>220–240 VAC (L-N) / 380–415 VAC (L-L)</td></tr><tr><td><strong>Max Current</strong></td><td>63 A</td><td>63 A</td></tr><tr><td><strong>Dimension</strong></td><td>46.8 × 17.8 × 21.3 mm (1MW)</td><td>46.4 × 53.0 × 21.3 mm (3MW)</td></tr><tr><td><strong>Accuracy</strong></td><td>±1% (active energy, resistive load)</td><td>±1% (active energy, resistive load)</td></tr></tbody></table>

#### 2. Installation Style

<table><thead><tr><th width="225"></th><th width="256">FLEX</th><th>MCBM</th></tr></thead><tbody><tr><td><strong>How it mounts</strong></td><td>Via voltage take-off wires — flexible positioning</td><td>Clips directly onto MCB body</td></tr><tr><td><strong>Breaker compatibility</strong></td><td>Universal — all circuit breakers</td><td>Verified with Siemens 5SY/5SL only</td></tr><tr><td><strong>Mounting direction</strong></td><td>N/A</td><td>Top-mounted (U1) or Bottom-mounted (D1) — to match your breaker's wiring direction</td></tr><tr><td><strong>Best for</strong></td><td>Retrofit projects, mixed or unknown breaker brands</td><td>New installations with Siemens 5SY/5SL</td></tr></tbody></table>

> 💡 If unsure about MCB compatibility, always choose **FLEX**.

#### 3. Connectivity

<table><thead><tr><th width="116">Variant</th><th width="137">Communication</th><th width="235">Architecture</th><th>API Style</th><th width="140">Typical Users</th></tr></thead><tbody><tr><td><strong>Tuya Wi-Fi</strong> (<code>*TW</code>)</td><td>Wi-Fi</td><td>BK7231N SoC (Tuya Firmware, Slave) + Metering MCU (Bituo Firmware, Master)</td><td>MQTT(Tuya Proprietary)</td><td>Tuya ecosystem, IoT beginners</td></tr><tr><td><strong>Tuya Zigbee</strong> (<code>*TZ</code>)</td><td>Zigbee</td><td>EFR32MG21 SoC (Tuya Firmware, Slave) + Metering MCU (Bituo Firmware, Master)</td><td>Tuya Proprietary Clusters</td><td>Tuya ecosystem with Zigbee hub</td></tr><tr><td><strong>Open Wi-Fi</strong> (<code>*EW</code>)</td><td>BLE + Wi-Fi</td><td>ESP8685 SoC (Bituo Firmware, Master) + Metering MCU (Bituo Firmware, Slave)</td><td>MQTT, HTTP, UDP, BLE</td><td>DIYers, System Integrators</td></tr><tr><td><strong>Std. Zigbee</strong> (<code>*TZ-U01</code>)</td><td>Zigbee 3.0</td><td>EFR32MG21 SoC (Bituo Firmware, Master) + Metering MCU (Bituo Firmware, Slave)</td><td>Standard Zigbee 3.0 Clusters</td><td>System Integrators, DIYers</td></tr></tbody></table>

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### Sub Pages

<table><thead><tr><th width="223">Model</th><th>Description</th></tr></thead><tbody><tr><td><a data-mention href="/product-document/spm-series/spm01-flex.md">SPM01 FLEX</a></td><td>1PN 63A Wireless Communication— Flexible-Installation</td></tr><tr><td><a data-mention href="/product-document/spm-series/spm01-mcbm.md">SPM01 MCBM</a></td><td>1PN 63A Wireless Communication— MCB-Mounting </td></tr><tr><td><a data-mention href="/product-document/spm-series/spm02-flex.md">SPM02 FLEX</a></td><td>3PN 63A Wireless Communication— Flexible-Installation</td></tr><tr><td><a data-mention href="/product-document/spm-series/spm02-mcbm.md">SPM02 MCBM</a></td><td>3PN 63A Wireless Communication— MCB-Mounting</td></tr><tr><td><a data-mention href="/product-document/spm-series/spm01r-flex.md">SPM01R FLEX</a></td><td>1PN 63A Wired Communication— Flexible-Installation</td></tr><tr><td><a data-mention href="/product-document/spm-series/spm01r-mcbm.md">SPM01R MCBM</a></td><td>1PN 63A Wired Communication— MCB-Mounting </td></tr><tr><td><a data-mention href="/product-document/spm-series/spm02r-flex.md">SPM02R FLEX</a></td><td>3PN 63A Wired Communication— Flexible-Installation</td></tr><tr><td><a data-mention href="/product-document/spm-series/spm02r-mcbm.md">SPM02R MCBM</a></td><td>3PN 63A Wired Communication— MCB-Mounting</td></tr></tbody></table>

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### Related

[SPM/SDM Zigbee Cluster Reference](/device-api/spm-sdm-zigbee-cluster-reference.md)

[Modbus TCP Map - ESP32-8685](/device-api/spm-sdm-open-wi-fi-api-overview/modbus-tcp-map-esp32-8685.md)