SPD Monitor (ESM SPD Monitoring Module) is a smart SPD monitoring terminal developed by FEXLINK. It monitors key parameters of surge protective devices in real time, including leakage current, temperature, voltage and lightning strike count, with the Proprietary Lifetime Prediction Algorithm for SPD health assessment and failure warning.

What parameters can SPD Monitor measure?

It monitors multi-dimensional parameters including microampere-level leakage current, SPD body temperature, wide-range operating voltage, and 0.1kA sensitive lightning strike count, with 200+ fully open registers and seamless Modbus integration.

How does SPD Monitor predict SPD lifetime?

Based on multi-dimensional data including leakage current growth trends, temperature rise changes and cumulative lightning energy, the FEXLINK Proprietary Lifetime Prediction Algorithm dynamically estimates remaining SPD lifetime and provides early warnings before failure, enabling timely replacement by O&M personnel.

Electrical Safety

SPD Monitor

Name: SPD Monitor (ESM SPD Monitoring Module)
Brand: FEXLINK

High-precision comprehensive sensing, making SPD health transparent

Integrating "measure, compute, display, intelligize" in one. Self-developed 10μA leakage current sensor with 100x improved accuracy. Achieves multi-dimensional status monitoring and degradation analysis of leakage current, temperature, voltage, lightning count and grounding status, with proprietary lifetime prediction algorithm - a revolution from "reactive replacement" to "proactive maintenance".

10μA

Leakage Current Accuracy

0.1kA

Lightning Count Sensitivity

200+

Accessible Registers

Microampere Leakage Monitoring Lifetime Prediction Algorithm Modbus-RTU 35mm DIN Rail Mounting 36mm Compact Width

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Product Overview

SPD Monitor (ESM SPD Monitoring Module) is an all-element smart SPD monitoring terminal integrating "measure, compute, display, intelligize". The product features a self-developed 10μA leakage current sensor with 100x improved accuracy, and uses algorithm models trained on massive field data to achieve multi-dimensional status monitoring and degradation analysis.

It monitors leakage current, body temperature, voltage, lightning count, grounding status, SPD telemetry and upstream breaker status in real time, dynamically computing a 0–100.0% lifetime value from 4 key factors to build a millimeter-precision SPD health profile, leaving no hazard hidden.

Widely used in industrial parks, railways, ports, airports, agriculture, mining, equipment, meteorology, water utilities, environmental protection, renewable energy and other fields. Based on high-precision feature data capture and analysis, it truly realizes degradation trend and degradation ratio functions, making it the ideal "IoT + Lightning Protection"Terminal.

Comprehensive Sensing Matrix

Microampere-level leakage current monitoring (10.0~3000.0μA), early degradation warning.
Precision temperature tracking (-30~125°C), preventing thermal breakdown.
0.1kA sensitive lightning strike counter, recording 0~9999 surge events.
Proprietary Lifetime Prediction Algorithm, quantifying remaining value.

Product Features

10μA-class Leakage Current Sensing

Self-developed 10μA leakage current sensor with 100x improved accuracy. Uses algorithm models trained on massive field data for multi-dimensional status monitoring and degradation analysis.

Proprietary Lifetime Prediction Algorithm

Dynamically computes 0–100.0% lifetime value from 4 factors: telemetry, count, temperature, leakage. Programmable alarm thresholds enable a shift from "reactive replacement" to "proactive maintenance".

Multi-level Smart Alarm Linkage

Dual protection with local audible/visual + remote communication. Triggers alarms when leakage >3000μA, temperature >60°C or lifetime <20%, uploaded in real time via RS485/MQTT.

Open Protocol, Seamless Integration

Standard Modbus RTU protocol, 200+ accessible registers fully open. Supports RS485 networking and MQTT cloud access, configurable byte order, zero integration barriers.

Full-Parameter Status Query

Enter multi-level query menu via panel buttons to view SPD lifetime, three-phase leakage, temperature, voltage, lightning strike count, grounding and other full-dimensional data, precise visualization of hidden risks.

Compact and Flexible

Default 7-segment display, optional OLED; physical buttons for convenient field query and configuration; pluggable terminals, 35mm DIN Rail Mounting, 36mm Compact Width, easy to deploy even in tight spaces.

Selection Guide

Model Naming Rules

ESM - 1 1 1 1 2 - R

Power

1=DC5V / 2=AC220V

Display

1=7-segment / 2=OLED

Phase

0=None / 1=Single-phase / 3=Three-phase

Current Parameter

0=None / 1=0.05~2.4mA (2.4mA/480mV silver coil)

Version

1=Basic / 2=Flagship

Communication

R=RS485 (Modbus)

Model	Power Supply	Display	DI Inputs	Grounding Status	Lightning Strike Count	Temperature	Leakage Channels	Voltage Channels	Lifetime Prediction	RS485
ESM-21001-R	AC 220V	7-segment	2-ch	1-ch	1-ch	1-ch	-	-	-	Yes
ESM-11112-R	DC 5V	OLED	2-ch	1-ch	1-ch	2-ch	1-ch	1-ch	Yes	Yes
ESM-11312-R	DC 5V	OLED	2-ch	1-ch	1-ch	2-ch	3-ch	3-ch	Yes	Yes
ESM-21112-R	AC 220V	OLED	2-ch	1-ch	1-ch	2-ch	1-ch	1-ch	Yes	Yes
ESM-21312-R	AC 220V	OLED	2-ch	1-ch	1-ch	2-ch	1-ch	3-ch	Yes	Yes

* Digital monitoring is used for SPD telesignaling and upstream breaker status. For other configurations, please contact sales for customized solutions.

Technical Parameters

Basic Parameters

Operating Voltage	DC 4.75~5.25V(5V model)/ AC 160~280V(220V model)
Power Consumption	≤ 2W
Operating Temperature	-20℃ ~ 60℃
Operating Humidity	< 95%
Weight	150g
Dimensions	36 × 110 × 69mm(L×W×H)
Enclosure Material	Thermoplastic UL94V0
Protection Rating	IP20
Mounting	Standard 35mm DIN Rail Mounting
Display	7-segment / OLED (optional)
Communication	RS485
Protocol	Modbus

Monitoring Functions

DI Input	Dry contact input, built-in power, 2-ch (monitoring SPD telesignaling and upstream breaker status)
Grounding Status	Grounding loop monitoring, 1-ch
Lightning Strike Count	0~9999 times, min trigger 0.1kA
Temperature	NTC measurement: -30~125°C, accuracy ±1°C
Leakage Current (AC)	50.0~2400.0μA, accuracy ±20μA
Voltage (AC)	0~600.0V, accuracy ±1V
Lifetime Prediction	0~100.0%, dynamically calculated from telesignaling/count/temperature/leakage
Alarm Output	Local audible/visual + remote communication, programmable threshold

Installation Instructions

Installation Dimensions

36mm

Width

110mm

Height

69mm

Depth

35mm

Standard DIN Rail

Sensor Description

SPD Monitoring Module sensor accessories

Sensor	Specification	Applicable Version
Lightning Strike Count Magnetic Ring	Aperture 12mm, cable length 1m	Basic, Flagship
Leakage Current Coil	4 turns, ratio 2.4mA/480mV, aperture 11mm	Flagship
NTC Temperature Sensor	Resistance 10kΩ (R25°C), cable length 15cm	Basic, Flagship

Interface Diagram

Wiring Definition

Terminal	Name	Description
L / N	Power	L: Live; N: Neutral (220V model)
5V / GND	Power	5V: Positive; GND: 0V (5V model, mutually exclusive with 220V)
A / B	RS485 Communication	A: RS485 A terminal; B: RS485 B terminal
DI1	Digital Input 1	Telesignaling input, other end to GND, polarity-independent
DI2	Digital Input 2	Breaker input, other end to GND, polarity-independent
T	Temperature	NTC temperature input, other end to GND, polarity-independent
C+ / C-	Lightning Strike Count	Lightning strike count input, polarity-independent
PE	Grounding Status	Grounding input, requires loop between live L and ground wire

Note: 220V AC input and 5V DC power input are mutually exclusive. Do not connect both simultaneously.