A Non-Operational Macromatic Product After a Period of Time in Service

Saturday: February 7, 2015 : Knowledgebase General


Issue:

I have a Macromatic relay that has stopped working. The product was working fine one day and then stopped functioning the next. What’s wrong?

Solution/Resolution:

Most Macromatic products have either a fusible resistor or a fusible trace on the PCB that acts like a fuse. This protects the circuitry from excessive transient voltages or over voltage conditions. If an over voltage or excessive transient condition occurs, this resistor or fuse track will open immediately preventing more dangerous possible failure modes.

Overvoltage events occur when voltage greater than the maximum rated input voltage are applied to the product. Transient voltages, often called “spikes”, occur very rapidly and cannot be measured using a simple multimeter. They can be caused by industrial equipment, utility power switching, and electrical storms. Macromatic products are designed and tested to handle significant voltage transients and to operate up to 110% of nominal input voltage levels. If transient energy exceeds the safe limits of our device, the resistor or fuse trace will open in order to protect operators and equipment. Once this occurs the product is no longer operational.

Troubleshooting

In order to determine if the protection is open, follow the steps for the appropriate product series. For any product not listed below, please contact Macromatic.

The troubleshooting method shown below is to be done for the following products:

  • All TR-5 & TR-6 Series Time Delay Relays
  • TD-7 Series Time Delay Relays
  • TD-8 Series Time Delay Relays
  • SS-6 & SS-8 Series B Time Delay Relays
  • SS-4 Series B Time Delay Relays
  • All THR Series Time Delay Relays
  • All V Series Voltage Monitor Relays (except VAKPU & VWKPU Series–see below)
  • All C Series Current Monitor Relays
  • All ARP Series Alternating Relays
    • Obtain a ohmmeter that reads up to 40 Meg ohms.
    • Connect the (+) side of the ohmmeter to L2 (N) (-) shown on the wiring diagram of the unit.
    • Connect the (-) side of the ohmmeter to L1 (L) (+) shown on the wiring diagram of the unit.
    • If the protection resistor or fuse track is still good, a reading of 1-40 Meg ohms should be seen on the ohmmeter. If the protection resistor or fuse trace has opened, the ohmmeter will read open & there will be near infinite resistance.

The troubleshooting method shown below is to be done for the following products:

  • All PMPU, PMP120, PMDU, PMD120, VAKPU, and VWKPU Phase monitor relays
    • Use an ohmmeter that reads up to 10 Kilohms.
    • Connect the (+) side of the ohmmeter to Phase A (Phase B for PMD products) shown on the wiring diagram of the unit.
    • Connect the (-) side of the ohmmeter to Phase C shown on the wiring diagram of the unit.
    • If the protection resistor or fuse track is still intact, a reading of 400 ohms to 10k ohms should be seen on the ohmmeter. If the protection resistor or fuse track has opened, the ohmmeter will read open & there will be near infinite resistance.

NOTE: Do not attempt to repair the unit yourself; opening of the unit voids the warranty and could result in unsafe operation. The damaged product should be replaced and you might consider installing transient and/or overvoltage protection within your application to prevent any recurrences. Please note that damage of this type is caused by operation outside of specified voltage limitations so warranty repair/replacement is not provided.

If you would like assistance in troubleshooting this issue or the product you have is not listed above, please contact Macromatic.

©2018 Macromatic Industrial Controls, Inc.

W134N5345 Campbell Drive
Menomonee Falls, WI 53051

800-238-7474 • 262-781-3366

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