Video: RMM – Product

Video transcript

How the RMM watches the stator insulation of motors and generators while they run, what it measures, how it reads the operating conditions alongside, and what it has found in real machines. Motors and generators are critical assets. Studies by IEEE and EPRI attribute up to 40% of electrical failures on high-voltage motors to the stator insulation, and most winding and cable faults are driven by partial discharge. It grows slowly, so the warning is there if somebody is watching.

The RMM is a continuous partial discharge monitor that also records the operating dynamics of the machine. It acquires every channel at the same time, calculates the quantities defined by IEC, stores up to two years of data, and keeps working on its own, with or without a PC connected. 15 partial discharge channels per module acquired concurrently. 70 dB of dynamic range, from 3 mV to 10 V with no gain adjustment. A bandwidth of 1 to 20 MHz,

a phase resolution of 7.5 degrees, and 32 magnitude windows. monitor is one unit with three sections, the power supply, the main monitor for the operating inputs, and the partial discharge monitor with its channels. Status lamps show alarm, warning, and the state of the unit, and Ethernet and USB are on the front. Partial discharge alone does not say enough. It has to be read against what the machine was doing.

So, besides the discharge channels, the RMM takes six winding temperatures, three load currents, three voltages, and six user-defined 4 to 20 mA signals. Out go Ethernet, USB, and RS-485 with Modbus, and dry contacts for alarm and monitor health. Coupling capacitors at the line terminals only see the discharge close to them, about 10 to 15% of the winding. The RTD sensors are already inside the slots, spread along the winding, and they respond to the high-frequency content of the discharge.

Through the RTDPD module, the RMM uses them as discharge sensors, and sees deep into the winding without new sensors. Results come in every format the industry uses. Phase resolve patterns in two and three dimensions, the polar view around the phase circle, the pulse height distribution, and the trend of every quantity over time, with several channels on the same screen. trend is where a monitor earns its place. Magnitude, pulse count, and discharge intensity of every channel,

month after month, next to the operating conditions. A channel that starts to climb points at the part of the winding that needs attention. real case, 6.6 kV motors drive critical compressors, monitored by an RMM for years. The data showed a fast increase in discharge on one of the RTDs. The motor was taken out for a planned inspection, the insulation defect was found and repaired, and the levels dropped back. The customer estimated the saving, planned against forced outage, at $91,000. A

second case, a 13.8 kV compressor motor. The monitor installed before only gave maximum magnitudes, between 1,500 and 2,000 mV, and it was in constant alarm. Phase resolve data showed floating discharges coming from the switchgear. With the RMM's noise cancellation, the real activity of the motor was 200 mV or less, and the nuisance alarm stopped. The RMM is more than a discharge monitor. It also performs motor current signature analysis to detect broken rotor bars in

induction machines, and it works on machines fed by variable frequency drives. It connects to existing sensors of any brand, which saves the purchase, engineering, and installation of new ones. It is mounted stand-alone, on a panel, or in an enclosure. For hazardous areas, there is a 316 stainless steel enclosure with a gasket flange, certified for Class 1 Division 1, Class 2 Division 1, and Class 1 Zone 1. Its place is any rotating machine that cannot be allowed to fail. Turbine and hydro generators and power plants,

large-medium and high-voltage motors driving critical processes, drive-fed machines, and installations in hazardous areas. figures, 15 channels, 70 dB, 1 to 20 MHz, 8 MB of memory, and a supply of 90 to 264 V AC or 100 to 300 V DC. Partial Discharge Detection from Amperis.