The Unipower HPL500MB is an advanced motor load monitor and shaft power monitor that measures true motor kW and communicates over Modbus RTU. One unit covers 3 x 100-575 Vac and 1 x 100-400 Vac, with direct measurement up to 40 A, so you can standardise on a single device for most three phase motor supplies. Dual programmable relays, a scalable analogue output and integrated Modbus communications provide fast, accurate protection and live load data for pumps, conveyors and other critical machinery.
🔧 Technical Highlights
- Supply and measuring voltage: 3 x 100-575 Vac and 1 x 100-400 Vac (supply voltage equals measuring voltage), single or three phase.
- Current range: Up to 40 A direct via feed through tube (use n:5 CTs above 40 A); internal ranges from approx. 0.5 A to 40 A.
- Measured value: True motor load in kW with digital display of kW and kW percent of scaled range.
- Shaft power calculation: Optional calculation of shaft output power P2 based on modelled motor efficiency.
- Output relays: 2 independent relays, freely configurable as Min or Max limits (Min or Max or Off) with one SPDT and one SPST contact.
- Analogue output: Scalable 0-20 mA or 4-20 mA output proportional to measured kW or percent load.
- Timers and masking: Individual trip delay timers for both relays plus start up surge masking to avoid nuisance tripping.
- Peak detectors: Built in min and max load memory simplifies commissioning by capturing normal operating load.
- Two speed motors: Input for active limit selection lets you switch limit sets when the motor runs at different speeds.
- Modbus RTU: Modbus RTU slave over RS485 for live motor load, status and parameter access from PLC, HMI or SCADA.
- Programming: Simple 3 button front panel navigation; optional HPL500H hand held programmer for remote setup and diagnostics.
- Mounting: Compact DIN rail or panel mounting, normally installed ahead of any frequency inverter on balanced loads.
✅ Benefits
- Universal voltage range allows one model to cover most three phase motor supplies worldwide.
- True kW based supervision follows real shaft load and torque, not just current.
- Protection and data in one device using dual relays, analogue output and Modbus RTU.
- Often eliminates the need for extra field sensors such as pressure or level switches.
- Fast, configurable response detects real faults quickly while avoiding nuisance trips.
🚀 Typical Applications
- Pumps: dry run protection, blocked suction, closed discharge valve and cavitation detection.
- Screw and belt conveyors: jam detection, overload protection and material build up monitoring.
- Crushers, grinders and screens: detection of product build up, foreign objects and varying material density.
- Scrapers and clarifiers: torque overload protection on scraper bridges and rotating machinery.
- Fans and blowers: detection of broken belts, closed dampers and abnormal airflow conditions.
HPL500MB gives you far more than a simple current relay. It is a complete motor load protection and monitoring platform that measures true motor kW, calculates shaft power, drives alarms and trips and shares real time load data across your Modbus network.
FAQs
- Q: Can I use HPL500MB as the main protection for my pump?
A: Yes. HPL500MB is designed to act as the main motor load protection for pumps and other driven machines. It can trip on both overload and underload, while also sending live load data to PLC or SCADA for alarms and trending.
- Q: Do I always need external CTs with HPL500MB?
A: No. HPL500MB measures up to 40 A directly via its feed through terminals. External n:5 CTs are only required when the motor current is above 40 A.
- Q: How do I get data from HPL500MB into my control system?
A: You can use either the 0-20 mA or 4-20 mA analogue output for a simple load signal, or connect over Modbus RTU to read detailed values and status in PLC, HMI or SCADA.