=== Differences between the Siemens SENTRON PAC2xxx, PAC3xxx, and PAC4xxx ===
The differences in structure among the Siemens SENTRON PAC2xxx, PAC3xxx, and PAC4xxx power monitoring series are summarised below, focusing on their physical placement, measurement accuracy, communication capabilities, and compliance status.

**SENTRON PAC Family Comparison Matrix**

^Technical Category^PAC2xxx Family (e.g., PAC2200)^PAC3xxx Family (e.g., PAC3120, PAC3220)^PAC4xxx Family (e.g., PAC4220)|
^Primary Device Application|Cost-sensitive sub-metering and individual breaker tracking.|Standard automation integration, feeder monitoring, and PLC bridging.|High-end power quality network analysis and historical tracking.|
^ Enclosure & Installation Style|Compact DIN Rail Mounting (or specialised distribution setups).|Square Panel Mount (96x96 mm Front); select models have blind DIN rail alternatives (PAC3200T).|Square Panel Mount (96x96 mm Front panel integration).|
^Integrated Communication Interfaces|Modbus RTU or Modbus TCP (hardwired variant decided upon purchase).|Integrated Modbus RTU or single/dual-port Modbus TCP.|Upgraded dual-port Modbus TCP supporting up to 12 parallel links.|
^Expansion Slot Capabilities|None (No modular physical plug-ins supported).|1 Slot available for optional PROFINET, PROFIBUS, or alternative networks.|2 Slots available for dual communication modules and extra physical I/O expansion.|
^Supported Network Configurations|1-phase, 2-phase, or 3-phase (up to 3-wire or 4-wire connections).|1-phase, 2-phase, or 3-phase (3-wire or 4-wire configurations).|1-phase, 2-phase, or 3-phase (3-wire or 4-wire configurations).|
^MID Billing Certification Status|Yes (Dedicated factory-calibrated MID variants are available).|Yes (Dedicated MID variants are available for modern models like PAC3120/3220).|No (Engineered as an analytical instrument rather than a direct tenant sub-billing meter).|
^Active Energy Accuracy Limits|Class 1 (Baseline industrial energy compliance).|Class 0.5S (Standard high-precision industrial automation billing).|Class 0.2 / Class 0.2S (Laboratory/revenue grade high-precision resolution).|
^Harmonics & Waveform Distortion Limits|Total Harmonic Distortion (THD) baseline viewing only.|Individual odd harmonics tracked up to the 31st harmonic.|Full harmonic network capture up to the 64th harmonic.|
^Onboard Historical Data Memory|Minimal (Only tracks real-time points and running total variables).|None (Relies entirely on external SCADA or PLC network recording).|Integrated Storage (Equipped with up to 8 GB internal memory for logging events, load profiles, and dips/swells).|


=== Some Sentron types compare ===

^Unit Model^Base & Optional Communication Protocols^Network Configuration (Phase/Wire)^MID Certification Status^Accuracy Limits (Active Energy)^Harmonic Limits & Features|
^PAC2200|Modbus TCP or Modbus RTU (Fixed variant via hardware selection)|1-phase, 2-phase, or 3-phase (up to 3-wire/4-wire)|Yes (Dedicated MID variants available)|Class 1 (IEC 62053-21) / Class B (MID)|Total Harmonic Distortion (THD) only|
^PAC3100|Modbus RTU (Integrated); No optional slots|1-phase, 2-phase, or 3-phase (3-wire/4-wire)|No|Class 1 (IEC 62053-21)|No structural harmonics tracking|
^PAC3120|Modbus RTU (Integrated)|1-phase, 2-phase, or 3-phase (3-wire/4-wire)|Yes (Dedicated MID variants available)|Class 1 (IEC 61557-12)|THD for Voltage and Current|
^PAC3200|Modbus TCP (Integrated). Optional: PROFINET, PROFIBUS, Modbus RTU|1-phase, 2-phase, or 3-phase (3-wire/4-wire)|No|Class 0.5S (IEC 62053-22)|Odd harmonics up to the 31st|
^PAC3200T|Modbus TCP (Integrated). Optional via Proxy: PROFINET|1-phase, 2-phase, or 3-phase (3-wire/4-wire)|No|Class 0.5% (IEC 61557-12)|THD and asymmetry limits|
^PAC3220|2x Modbus TCP (Dual RJ45 port). Optional: PROFINET, PROFIBUS|1-phase, 2-phase, or 3-phase (3-wire/4-wire)|Yes (Dedicated MID variants available)|Class 0.5S (IEC 62053-22)|Odd harmonics up to the 31st|
^PAC4200|Modbus TCP (Integrated). Optional: PROFINET, PROFIBUS, Modbus RTU Gateway|1-phase, 2-phase, or 3-phase (3-wire/4-wire)|No|Class 0.2 (IEC 61557-12)|Comprehensive tracking up to the 64th|
^PAC4220|2x Modbus TCP (Dual port, 12 links). Optional: PROFINET, PROFIBUS|1-phase, 2-phase, or 3-phase (3-wire/4-wire)|No|Class 0.2 (IEC 61557-12)|Comprehensive tracking up to the 64th|
^Sentron 9410|Dual-port Modbus TCP, Modbus RTU, ION Protocol, IEC 61850, DNP3|1-phase, 2-phase, or 3-phase (3-wire/4-wire)|No (Meets ANSI C12.20 Revenue class)|Class 0.2S (Ultra-high precision)|Individual harmonics up to the 63rd + Waveform capture|
^Sentron 9810|Dual-port Modbus TCP, Modbus RTU, ION Protocol, IEC 61850, DNP3, DLMS|1-phase, 2-phase, or 3-phase (3-wire/4-wire)|No (Meets ANSI C12.20 Revenue class)|Class 0.1 (Laboratory grade standard)|Advanced grid analysis up to the 127th + Transient recording|