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I recently got a new heat pump which has 3 parts:

  • Indoor pump
  • Outdoor pump
  • electrical heater

The picture below shows the configuration in the fuse box enter image description here

Before the main fuse (FI in my country 230V@50Hz) is an energy meter SDM-72 to monitor the heatpumps power consumption. In the specs the basic current is rated at 10A and the maximum rated current at 100A.

From my simple calculation I get

  • L1: 13A + 6.5A ~ 20A
  • L2: 13A + 14.3A ~ 28A
  • L3: 13A

This would mean, that the energymeter is always operated over the basic current, which affects its accuracy and lifespan. Should I replace it with an higher rated energy meter?

Also there is some concern of the position of the energy meter since the FI should trigger when a delta current of 30mA is recognized. If there is an additional consumer between the FI and the circuit breaker there is also an additional impedance which might delay the reaction of the FI. Should the energy meter before or after the FI?

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    \$\begingroup\$ Why not ask BG-ETech? \$\endgroup\$
    – Transistor
    Commented Nov 17, 2020 at 13:01
  • \$\begingroup\$ I am also unsure that this is the correct way to monitor the power consumption, since not all phases draw the same amount of current \$\endgroup\$
    – v3xX
    Commented Nov 17, 2020 at 13:06
  • \$\begingroup\$ My computer blocked the link in the question as insecure. The comment "I am also insure ...." Should be added to the question. \$\endgroup\$
    – user80875
    Commented Nov 17, 2020 at 14:02
  • \$\begingroup\$ I expanded the question \$\endgroup\$
    – v3xX
    Commented Nov 17, 2020 at 17:05

1 Answer 1

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Operating over 10 A probably does affect the accuracy. Check the meter specs to determine if that effect is more than you would like. The meter lifetime may be affected, so look at the spec details concerning lifetime. If the meter is designed for measure 3-phase power, it should be able to handle the range of current imbalance that you have. The meter specs may have more about that.

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