Canned Motor Pump Rotary Guardian DRG

The industry standard for sealless pump monitoring and reliability for over 40 years

■ Monitor current conditions

■ Develop data-based preventative maintenance schedules

■ Monitors and indicates rate of radial bearing wear

■ Detects lost phase

■ Shows reverse rotation

■ The only bearing wear monitor on the market that operates with Variable Frequency Drives

Principle of Operation

The DRG meter operates on the principle of induced voltage. A magnetic field is created in the DRG coils by the current flowing through the stator winding. In addition, a magnetic field is created by induced currents in the rotor.
When the rotor is perfectly centered in the stator, the two magnetic fields are essentially concentric or balanced.
When bearing wear occurs and the gap “B” between the rotor and stator decreases, a magnetic flux created by the imbalance in the magnetic fields causes an induced voltage in the DRG coils. When bearing is worn out to increase the gap (a), while to decrease the gap(b) the difference sum between the A and B coil with the higher harmonics portion and the fundamental wave is increased substantially.
This voltage is indicated on the DRG voltmeter. The meter is mounted on the pump terminal box as standard but is available as remote panel-mount.

DRG with Phase Sequence Sensor in Operation

TRG initial indication varies from pump to pump. Users can record the initial value to establish a baseline. This determines a point from which to monitor the wear rate of the bearings and establishes preventative maintenance schedules.