Case Study - Motor Test Rig

Designing a mobile motor testing rig in a tight time frame for a range of DC & AC motors.

The Goal

The customer approached I S Systems with a requirement for Motor Testing Rig. The rig needed to be capable of testing a variety of AC & DC motors, some free-spinning and some loaded, across a wide range of voltage, current and AC frequencies. With a tight time frame, as well as the requirement to take several different modes of operation, this project represented a significant design challenge.

The Solution

I S Systems first began by tackling the requirement for flexibility & quick installation time, and the panel suite was constructed in the I S Systems workshop exactly as it would be on site. This allowed us to fully factory test the solution, then simply disconnect it, transport it to the site, and reconnect it – and the rig was available to commence testing in just 3 days.

The inverters used in the Motor Test Rig are operated in an unusual mode with the ability to independently control voltage and frequency. This offers some significant advantages in using physically small, higher frequency transformers to deliver rated current right down to near zero voltage. Two of the inverters can be operated in a synchronised mode where their output voltages are actively synchronised by a phase-locked-loop control board developed in-house by I S Systems.

The Control System consists of an S7 PLC with a Profibus interface to each converter, and a Siemens touch-screen HMI interface resulting in operator training times in just a few minutes. The system offers overcurrent detection, which can recognise fault conditions and initiate a controlled power flow reduction to reduce wear on switchgear and fuses.

Rectifier and inverter for motor test rig

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