Time Mark 3-Phase Monitors: Applications and benefits


Time Mark 3-phase monitors are specially engineered to meet the demands of today’s industrial power systems. They are suitable for detecting various abnormal power conditions including phase reversals, phase loss, voltage unbalance, under voltage and over voltage. The design of these 3-phase monitors make them suitable for use in monitoring and protecting a broad array of industrial systems.


Figure 1: Instantaneous voltage waveforms for one cycle of an ideal 3-phase system.

Time Mark 3-phase monitors are available in a broad range of models including 153, 15, 158B, 18, 19, 20, 20AA, 21, 22, 25, 2500, 2500D, 2501 and 2522B series. A complete list of these 3-phase monitors is available here.

Applications of Time Mark 3-Phase Monitors

A typical 3-phase monitor consists of a microcontroller-based electronic circuit and an electromechanical relay. The electronic circuit is responsible for sensing the power conditions and driving the relay. The relay is energized or de-energized depending on the conditions of the supplied power.

Time Mark 3-phase monitors are designed to detect various abnormal power conditions including phase reversals, unbalanced voltages, phase loss, under voltage and over voltage conditions.

  • Unbalanced voltage conditions: Voltage unbalance in 3-phase systems affects the overall performance of motors and significantly reduces their operational life. Time Mark 3-phase monitors such as 2002-Series and 200-Series are designed to detect unbalanced voltage conditions in 3-phase power systems, thereby helping to protect electrical equipment.
  • Phase rotation: Some electrical systems such as grinders, elevators and compressors are very sensitive to phase rotations. For such systems, it is critical to ensure that a suitable device is used to monitor phase rotations. 3-phase monitors such as 153-Series and 2532-Series are engineered to monitor and protect sensitive equipment from the damaging effect of incorrect phase rotations.
  • Phase loss: In a 3-phase power system, loss of one phase usually causes connected equipment to draw excess current from the other two phases. Apart from causing overheating in motor windings, a phase loss condition can also cause motors to experience excessive vibrations. Time Mark 3-phase monitors such as 158B, 18-120, and 19-120 are specially engineered to detect phase loss and protect connected equipment.
  • Abnormal power conditions: Some 3-phase monitors such as 20-Series, 20AA-Series, 21-Series, 2500-Series, 2500D-Series, 2501-Series, 246-Series, 252-Series, 257-Series, 258-Series and 2522-Series are designed to detect a variety of abnormal power conditions. These monitors are suitable for monitoring under voltage, over voltage, phase reversal, voltage unbalance and single phasing conditions in 3-phase electrical systems.

Installing a 3-phase monitor (158B)

The 158B 3-phase monitor is designed to detect low voltage, phase reversal and phase loss in 3-phase power systems. The procedure for installing this monitor is as follows:

  • Mount the monitor in a suitable enclosure and connect ¼” terminal lugs to the input power supply wires.
  • Connect the terminal lugs to the terminals of the monitor labelled ∅A, ∅B, and ∅C.
  • Confirm the monitor is connected in a clockwise phase rotation using a rotation indicator.
  • Connect ¼” terminal lugs to the wires of the load control circuit.
  • Connect the terminals of the load control circuit to the terminals of the monitor labelled C and NO.

Figure 1: 158B 3-phase monitor connection diagram

Benefits of using 3-phase monitors

Time Mark 3-phase monitors are suitable for monitoring a broad array of 3-phase power systems. The benefits of using these 3-phase monitors include the following:

  • Improved equipment service life. Subjecting electrical systems to abnormal power conditions degrades their service life and using monitors helps to mitigate such abnormal conditions.
  • Reduction in equipment failures and damages. Detecting and correcting abnormal power conditions helps to minimize equipment damages.
  • Reduction in downtime and equipment-related non-productive time.
  • Reduced maintenance costs due to improved protection.

Check out 3-Phase Monitors for more information about models, applications and installation of Time Mark 3-phase monitors.