Notes due to differences in load connections in 3-phase
There are delta connection and Y connection in the connection method of the 3-phase heater load. Both have the same effective power value, but there is a difference when the one-phase heater is disconnected. In the case of Δ connection, each line current is flowing, even if one phase is disconnected. Depending on the current value of the load, the load disconnection detection may not work and operation will continue. However, in the case of a transformer load, if the load becomes unbalanced, bias magnetism may occur, which may cause overcurrent and blow the fuse or damage the thyristor element. However, if a 6-element (6-arm) type is used, magnetic bias will not occur.
In the case of Y connection, one phase of each phase current will not flow, so the load release detection works and the operation of the PARACON stops.