• Gossen Metrawatt
  • Gossen
  • Camille Bauer

EM402: What should you watch when connecting energy meters with pulse output to a PLC?

The pulse output of energy meters is standardized in EN 62053-31 or DIN 43864 and has the following timing:

In order for the pulses to be detected with simple means, the ON state should be as long as possible, the restriction being determined by the set pulse rate. At high pulse rates and full load, the ON state must be short enough so that the minimum OFF time can still be maintained.

Choosing the shortest allowed ON state of 30ms and giving that signal to a controller's digital input card can cause impulse detection problems with some controllers with long cycle times and high program volumes. The remedy is often to select an ON state of 100 ms or longer.

For oversized converters or networks it may now be necessary to work with high pulse rates for better resolution. Due to the lower load, the pulse sequence will be so low that even the ON state may be longer than restricted by full load. In these applications, however, it must be ensured that the load on the network generally remains below the upper limit specified by the timing.