Introduction
Tanzania East Africa Gateway Terminal Limited (TEAGTL) is a major port logistics and cargo handling facility on Tanzania’s coastline. As part of an electrical infrastructure upgrade, a project was commissioned to supply and install a Schneider Electric iEM3255 energy meter (reference A9MEM3255) for accurate, legally compliant energy monitoring across the terminal’s distribution network.
Product Specification
The Schneider Electric iEM3255 (A9MEM3255) is a compact three-phase DIN rail energy meter built for commercial and industrial sub-metering.
- Model: iEM3255
- Reference: A9MEM3255
- Current Input: CT-based (external current transformers)
- Communication: Modbus RTU (RS-485) and Modbus TCP/IP
- Digital Input: 1 × DI — tariff switching or pulse input
- Digital Output: 1 × DO — kWh pulse or alarm relay
- Tariff: Multi-tariff (time-of-use energy accumulation)
- Certification: MID Approved — Class B (±0.5% accuracy)
- Mounting: 35 mm DIN rail
- Voltage Range: 57.7–240 V Ph-N / 100–415 V Ph-Ph, 50/60 Hz
Why the EM3255 Was Selected
- MID certification provides legally defensible billing data for port operators and terminal concessionaires
- CT-based input allows installation on live circuits without shutting down terminal operations
- Modbus RTU/TCP enables integration with the site BEMS and SCADA systems
- Multi-tariff engine captures TANESCO peak, shoulder, and off-peak rate bands accurately
- Compact DIN rail housing fits within existing switchgear panels
- Digital pulse output provides an independent kWh count for billing verification
CT-Based Installation
Split-core current transformers were clamped around live conductors, avoiding the need to isolate busbars or interrupt operations. CT ratios were matched to upstream protection ratings. Secondary outputs (1 A) were wired to the meter’s current input terminals, and voltage sensing was tapped from the board via 2 A MCB-protected connections. CT polarity was verified on all phases before energization.
Modbus Integration
The meter was configured on the site RS-485 Modbus RTU network with a unique slave address. Data points mapped to the TEAGTL energy monitoring platform include active power (kW), reactive power (kVAr), power factor, phase voltages and currents, total energy (kWh), and per-tariff registers T1, T2, and T3.
Commissioning Summary
All works were completed without disruption to terminal operations. Tests confirmed:
- Accuracy within MID Class B (±0.5%) at three load levels
- Correct CT polarity and ratio on all phases
- Modbus communication verified end-to-end with the BEMS gateway
- Multi-tariff switching validated across all three tariff periods
- Pulse output cross-checked against Modbus kWh registers
Full commissioning documentation — including CT ratios, Modbus address, register map, and tariff schedule — was handed over to the TEAGTL Facility Management team.
Conclusion
The Schneider Electric iEM3255 (A9MEM3255) delivers a MID-certified, Modbus-connected, and multi-tariff energy metering solution at Tanzania East Africa Gateway Terminal Limited. TEAGTL now has accurate, auditable energy data to support fair utility billing and energy management across the terminal.
