Ammeter Selector Switch

In the below image a panel have only 4 places for electric panel meter instillation and if we instill the three meter for voltage testing then we have only one place for ammeter and we don't have place to instill the three ammeters, so the ammeter selector switch make easy to test and measure the all phases L1 , L2 , L3 amperes with on panel ammeter by using the selector switch.

In the above image i shown the three voltage panel meters and one ammeter with selector switch
As given in pic the selector switch is used for measuring the current on different lines
In the ammeter S switch we have 4 menu 0,1,2 and 3 and on the 0 point it's off and 1 side the switch active the first CT and on 2 the L2 CT and on 3 the selector switch active or do connection the L3 CT to ammeter.as CT is connected in star so their will be one common point and that will be grounded 

n the above diagram i shown the three phase four wire supply with three CT coils. In the selector switch connect the all CT Coils connection to R,S,T. and get supply From A1 and A2 for ammeter. Note that this ammeter switch front menu available in different names such as 0-1-2-3 , L1-L2-L3 and R-S-T. Note that in the above diagram i connect all current transformers one one wire with a point which i shown with earth symbol and if you don't connect this common wire to A2, the connection and ammeter will also work properly.