--- title: "LV switchgear and switchboard monitoring | GridBit" description: "LV switchboard monitoring for secondary substations: current, voltage, power and power quality per phase, and the state of every feeder, fuse and protection." url: "https://www.gridbit.tech/solutions/switchgear-monitoring" language: "en" translation: "https://www.gridbit.tech/bg/solutions/switchgear-monitoring" --- # GridBit LV switchgear monitoring GridBit brings the low-voltage board of a secondary substation online. A network analyser measures current, voltage, power and power quality on every phase, and a voltage detector watches the outgoing feeders, fuses and protections. - Modbus modules and third-party sensors [Request a quote](https://www.gridbit.tech/contact?product=GridBit%20Switchgear%20Monitoring) - **voltage inputs on one SMU-3 detector**: 8 - **active power accuracy of MCU-4**: ±1 % - **harmonic orders the platform shows per phase**: 3 to 13 - **Modbus devices one gateway can read**: 127 The problem ## The first report often comes from a customer Below the secondary substation the operator often learns about a fault from the customers. Without data from the low-voltage board, a DSO faces: 1. 01 More frequent and longer interruptions, worse SAIDI and SAIFI How it works ## From the DIN rail to the platform The modules mount on the DIN rail of the board and share one Modbus RTU line with the gateway. 01 MCU ### Every phase of the busbar The MCU-4 network analyser measures voltage, current, active, reactive and apparent power, cos φ and energy on each phase. Its active power accuracy is ±1 %. [Open the module](https://www.gridbit.tech/hardware/mcu-4) 02 SMU ### A voltage check on every feeder The SMU-3 detector reads AC voltage on eight inputs, isolated by 5000 V from its supply and the bus. A feeder whose fuse has blown or whose protection has tripped shows up as an input without voltage. The relay unit (RLU) switches lines on a schedule or on command. [Open the module](https://www.gridbit.tech/hardware/smu-3) 03 GWU ### One gateway for the board The GWU-5 gateway reads up to 127 Modbus devices on one bus and sends their data with MQTT over 4G LTE, with 2G as fallback, or over Ethernet. [Open the module](https://www.gridbit.tech/hardware/gwu-5) 04 WDT ### Keeps the electronics running Surges and harmonics on the supply can make electronics hang. The WDT-1 watchdog relay follows the Modbus communication and, when it stops, operates its relay for a set time to restart the devices. [Open the module](https://www.gridbit.tech/hardware/wdt-1) 05 Platform ### The board in a browser The platform shows the busbar and every outgoing circuit, and the power quality of the past week, phase by phase. The platform ## Every circuit of the board on one screen ### The busbar and every circuit Current and voltage per phase with the minimum, average and maximum for the period, then the same for each outgoing circuit. ### Power quality over a week Voltage deviation, rapid voltage changes, asymmetry and harmonics from the 3rd to the 13th with the total distortion, per phase. Screens from the interface design, with sample data. Functions ## Set to your processes and systems 01 ### Automation Processes, tasks, analyses and reports set to the needs of the client. 02 ### Integration With systems of other vendors through standard protocols. 03 ### System configuration Devices, users and thresholds managed from the interface. Benefits ## Faster response, safer work ### Efficient operation Faults and disruptions are detected at once, response is quick and downtime is short. ### Safety Hazards are identified early, so crews act in time and the risk of accidents drops. In the field ## The same modules run in street lighting cabinets MCU-4 and SMU-3 already work in the field: they are part of GridBit street lighting management, the system that switches and measures street lighting cabinets across Bulgaria. [See street lighting management](https://www.gridbit.tech/solutions/street-lighting) - **street lighting cabinets**: 4 500+ - **municipalities**: 70+ ## Hardware in this system - Compact modules, combined as the substation needs - [Gateway GWU-5 4G LTE gateway for Modbus devices, with Ethernet and MQTT 4G LTE Cat 1 Mobile network, 2G fallback RS485 + Ethernet Modbus RTU and Modbus TCP](https://www.gridbit.tech/hardware/gwu-5) - [Gateway GWU-4 2G/4G gateway for Modbus RTU devices, two digital inputs 4G LTE Cat 1 Mobile network, 2G fallback RS485 Modbus RTU](https://www.gridbit.tech/hardware/gwu-4) - [Meter MCU-4 Three-phase network analyser with Modbus RTU 3P+N / 1P+N Pole configuration U, I, P, cos φ, E Measured parameters](https://www.gridbit.tech/hardware/mcu-4) - [Inputs SMU-3 Eight-channel AC voltage detector with Modbus RTU 8 Voltage detection inputs 280 VAC Maximum input voltage](https://www.gridbit.tech/hardware/smu-3) - [Watchdog WDT-1 Watchdog relay that restarts devices when Modbus communication stops Normally open Relay contact 250 VAC Max. relay voltage](https://www.gridbit.tech/hardware/wdt-1) ### Sensors and units for the board - TS2 Contact temperature sensor - TIR Optical, contactless temperature sensor - RLU Relay unit Electrical infrastructure digitalization ## Also on the same platform GridBit Street Lighting ### [GridBit street lighting management](https://www.gridbit.tech/solutions/street-lighting) Control and monitor street lighting cabinets from one system, with schedules that follow sunrise and sunset, measurements per phase and alarms for every cabinet. Learn more GridBit Transformer Monitoring ### [GridBit MV/LV transformer monitoring](https://www.gridbit.tech/solutions/transformer-monitoring) Temperature, load and alarms of the MV/LV transformer in a secondary substation, in real time. Sensors and a gateway go into the existing substation without changing the primary equipment. Learn more GridBit Asset Passportization ### [GridBit asset passportization](https://www.gridbit.tech/solutions/asset-passportization) An asset register for DSOs, with an asset passport for every secondary substation that holds its identification, technical parameters and connected generation. It works on its own or together with monitoring. Learn more Questions ## Short answers Another question? [Ask an engineer](https://www.gridbit.tech/contact) ### What does the system measure at the low-voltage board? Current, voltage, power and power quality on every phase, and the state of the outgoing feeders, fuses and protections. On the DIN rail, the MCU-4 network analyser measures each phase and the SMU-3 voltage detector reads eight inputs. ### Which power quality values does the platform show? Voltage deviation, rapid voltage changes, asymmetry and harmonics from the 3rd to the 13th with the total distortion, per phase. The busbar view adds current and voltage per phase with the minimum, average and maximum for the period. ### Does it work with systems and sensors from other vendors? Yes. The platform integrates with systems of other vendors through standard protocols, and third-party Modbus sensors connect to the same line as the GridBit modules. ### Are these the same modules as in street lighting cabinets? Yes. MCU-4 and SMU-3 are also part of GridBit street lighting management, which runs in more than 4 500 street lighting cabinets in more than 70 municipalities in Bulgaria. ## Ask for a proposal for your LV boards Tell us how many boards you want to monitor and which values matter to you. We propose the modules and the gateway and send a quote. [Request a quote](https://www.gridbit.tech/contact?product=GridBit%20Switchgear%20Monitoring) [office@add-bg.com](mailto:office@add-bg.com)