MBU Voltage monitoring

Power supply stability has an increasing influence on the availability and service life of electrical devices as well as on reliability in modern manufacturing processes. The MBU voltage monitoring device was specifically designed for that purpose: to detect deviations from nominal values in the applicable power supply.

High and low voltages are faults that occur frequently in the power grid. In modern power supply network systems, these grid faults arise with increasing frequency due to the increasing number of non-linear operating resources such as switching power supplies, frequency converters and electronic ballasts. The majority of grid faults can be traced back to problems with excessively low voltages.

Short-term surges cause damage to insulation, medium- to long-term overvoltage events result in thermal overload and, in the most minor cases, lead to a shorter service life for the affected components. Excessively low voltages in the range of 1–2 half-cycles cause malfunctions in which, for example, relays and contactors chatter or fail entirely. Longer periods of undervoltage caused by control faults, overloads, or faults in the grid (e.g. interruption in neutral conductor) may also result in thermal overloads, malfunctions, and irreparable damage to components.

The newly designed MBU voltage monitoring device from ComatReleco performs voltage measurements in 1- and 3-phase systems. It is extremely easy to operate. All user parameters can be adjusted via infinitely variable potentiometers. For the output, a change-over contact with 5A, 250 V AC is provided. A red status LED lights up when the alarm is active. The devices correspond to the IEC/EN 60255-1 standard, with a mounting dimension of 17.5 mm. The devices will be available as of Q4 2020.

The advantages are:

  • Wide range of monitoring features: reports when adjustable limit value is exceeded or not met, adjustable alarm delay time
  • Monitors all electrical quantities; depending on model:
    voltage, phase sequence, phase failure
  • Quick commissioning due to a potentiometer that can be easily adjusted


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