The 3 pin power cable is only used on Dinamica Generale indicators, but can be forced in to the 5 pin crown load cell ports on other indicators.  The load cell circuit is not meant to receive 12V power that the 3 pin provides.  That connection can potentially cause damage to the indicator.  If you are replacing a Dinamica Generale with other manufactures' indicators the 3 pin power cord has to be removed from machinery and replaced with an appropriate power cable for the new indicator.

Notice the similar size of the 5-pin Crown load cell port labeled "SENSOR" and the 3-pin power port. 

Another example of the 3-pin power port and the connector that plugs into it.