The **Moxa PT-7828-R-48** is a high-performance, Layer 3 managed Ethernet switch designed specifically for power substation automation. It adheres to the **IEC 61850-3** and **IEEE 1613** standards, ensuring reliable operation under extreme electromagnetic interference (EMI). ### 1. Core Technical Specifications The "R-48" designation specifically refers to the power configuration and mounting style of this unit. | Feature | Specification | | :--- | :--- | | **Total Ports** | Up to 28 ports (24 Fast Ethernet + 4 Gigabit) | | **Slot Configuration** | 3 slots for 8-port Fast Ethernet modules, 1 slot for 4-port Gigabit modules | | **Input Voltage** | 48 VDC (Range: 36 to 72 VDC) | | **Power Redundancy** | Dual isolated redundant power supplies | | **Operating Temp** | -40 to 85°C (-40 to 185°F) | | **Mounting** | 19-inch rack mounting | --- ### 2. Key Electronic Components & Design The electronic architecture is built for "zero packet loss" in high-voltage environments. #### Power Supply Unit (PSU) * **Isolated Design:** The 48 VDC input is galvanically isolated to prevent surges from the power grid from damaging the internal logic circuits. * **Redundancy:** The "R" in the model name indicates rear cabling, typically paired with dual power inputs to ensure that if one power source fails, the switch continues to operate without rebooting. #### Modular Interface System Unlike fixed switches, the PT-7828 uses a modular backplane. * **PM-7200 Series Modules:** The electronic heart of the I/O. These modules can be swapped to provide copper (RJ45), multi-mode fiber (ST/SC), or single-mode fiber connections. * **SFP Slots:** The Gigabit ports often utilize SFP (Small Form-factor Pluggable) transceivers for long-distance optical communication. #### Robust Internal Circuitry * **Fanless Design:** The electronics are engineered for high thermal efficiency, using heat sinks and chassis dissipation rather than fans (which are mechanical points of failure). * **Hardware-based Time Stamping:** Supports **IEEE 1588 PTP v2** (Precision Time Protocol) for nanosecond-level time synchronization across the grid. --- ### 3. Electronic Compliance & Protection The circuitry is hardened against environmental stressors typical in industrial sites: 1. **EMS (Electromagnetic Susceptibility):** High level of protection against electrostatic discharge (ESD), radiated RF, and electrical fast transients (EFT). 2. **Logic Separation:** The control plane (CPU managing the software) is electronically isolated from the data plane (ASICs moving the packets) to maintain stability during heavy traffic. 3. **Alarm Contact:** Includes a relay output (3 A @ 30 VDC) that can be wired to an external PLC or siren to signal power failure or port links going down. ---