Earth resistance tester TOHMY®

impedancecontinuityground

Product overview TOHMY® measures the impedance of grounding systems and automatically transmits measurement data remotely. Information is accessible through a mobile app or a centralized web platform and is recorded and monitored in real time. It includes a continuity detector to identify resistance increases caused by oxidation, poor connections or an open control bridge, enabling corrective action before critical failure. A machine learning algorithm predicts system evolution to anticipate maintenance interventions.

Key benefits

• Predictive maintenance: Continuous condition monitoring to anticipate failures and optimize interventions.
• Continuous monitoring: 24/7 supervision of grounding installations without scheduled on-site inspections.
• Immediate alerts: Automatic notifications when anomalies are detected.
• Remote access: Monitor installations from anywhere via web platform or mobile app.
• Lower maintenance costs: Reduce unnecessary inspections, travel and corrective actions while extending installation life.
• Regulatory compliance: Automatic storage of measurement records for traceability, audits and reports.
• Centralized management: Manage multiple TOHMY® devices across locations from a single online platform.

Models

• TOHMY® (model TG100): Measures grounding impedance using the fall-of-potential method.
• TOHMY+® (model TG200): Measures grounding impedance using the loop method.

TOHMY® (model TG100) — fall-of-potential method

• Measurement method: fall-of-potential.
• Channels: 2 independent measurement channels (ground - CPE - and continuity).
• Measurement connections: 5 female banana connectors, ~300 mm cable length, 5 conductors of 1.5 mm² (15 AWG).
• Measurement range: 0 to 2000 Ω (single scale).
• AC signal frequency: up to 2 kHz (optimal 100 Hz to 1 kHz).
• Error (both channels): ±3% or <0.5 Ω over working frequency and resistance ranges.

TOHMY+® (model TG200) — loop method

• Measurement method: loop method.
• Measurement sensor: 2 wound excitation cores generating voltage and 1 wound core for current reading; 8×1 mm² cable, 700 mm length.
• Suitable conductor diameter: up to 13 mm Ø (≈120 mm² cross-section).
• Measurement range: 0 to 500 Ω (single scale).
• AC signal frequency: 500 Hz to 2500 Hz.
• Accuracy: ±10% or <0.5 Ω over working frequency and resistance ranges.

Shared technical features

• Signal generator with sinusoidal waveform; self-calibration and self-test using precision resistors.
• Reading process duration: approx. 500 ms.
• Dimensions: 110 x 170 x 40 mm. Plastic housing in ASA material; IP68, weather-proof and UV-resistant.
• User interface: 2 push buttons (power on/off and device connection) and 4 LED indicators (operation & battery level, data network connection, device connection operation, acquisition & measurement activity).
• Power supply: 3.3 to 5.5 VDC — from 3 × 1.5 VDC AA batteries, external 5 VDC nominal supply (not included) or USB charger connection.
• Real-time clock (RTC) automatically synchronized via SNTP; schedule planner for measurement programming.
• Wireless communications: 2.5 GHz band for Wi-Fi (UDP) and optional Bluetooth with integrated antenna; Wi‑Fi station mode provides internet access and virtual COM port via USB.
• RF transmission power configurable between 10 and 20 dBm.
• MQTT client with connection to AWS broker (default) and secure encrypted layer using certificates.
• Monitoring accessible via mobile application through wireless connection.
• 5-pin extension port for external sensors (humidity, temperature, pH...), communication ports and/or external power supplies.
• Electromagnetic compatibility tested; CE marked. Electronics compliant with RoHS.
• Operating temperature range: -20 °C to +45 °C.

Caractéristiques / spécifications techniques

• Product family / commercial name: TOHMY® (includes TG100 and TG200).
• TG100 measurement method: fall-of-potential; range 0–2000 Ω; accuracy ±3% or <0.5 Ω; AC freq up to 2 kHz (optimal 100 Hz–1 kHz); 5 banana female connectors; cable ~300 mm, 1.5 mm² conductors.
• TG200 measurement method: loop; range 0–500 Ω; accuracy ±10% or <0.5 Ω; AC freq 500–2500 Hz; sensor cable 8×1 mm², 700 mm; supports conductors up to 13 mm Ø (~120 mm²).
• Common: sinusoidal signal generator, self-calibration, reading ≈500 ms, dimensions 110×170×40 mm, ASA plastic, IP68.
• Power: 3×AA (1.5 V) batteries or external 5 VDC or USB; supply 3.3–5.5 VDC.
• Connectivity: Wi‑Fi (2.5 GHz UDP), optional Bluetooth, virtual COM via USB, MQTT client (AWS default) with TLS certificates; RF power 10–20 dBm.
• Extras: RTC with SNTP sync, scheduling, continuity detector, mobile app and centralized web platform monitoring, 5‑pin extension port for external sensors.
• Compliances: CE marking, RoHS.
• Operating temperature: -20 °C to +45 °C.