• Din rail mounted
  • Protected terminals
  • Up to 9 primary inputs
  • 1 Amp or 5 Amp secondaries
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Din rail mounted summation current transformers enable the summing of several independent loads on different supplies.

An example: Three 3 phase supplies to be read by one KWh meter.

Supply 1: 200 Amps
Supply 2: 800 Amps
Supply 3: 1000 AmpS

Required for each supply are three main CT's of the above primary currents, one for each phase L1/L2/L3. Also required will be three, 3 input summation CT's, each of the summation CT's must be designated to a phase. The secondaries from the L1 phase main CT's should be fed to the inputs of the L1 designated summation CT, likewise the same applies for L2 and L3 phases. The secondary output from the summation CT's will then equal the sum of the three primary currents:-

200/5 + 800/5 + 1000/5 = 2000/5

The meter being used must therefore be calibrated for 2000/5.

The above example of summation CT's have unbalanced ratio inputs and therefore have to be manufactured to order. Balance ratio input summation CT's are usually ex-stock.

Summation CT's can also be used for subtraction purposes by reversing the polarity of the inputs. It is also possible to summate a mixture of single phase and three phase supplies.

Please consult our sales office for application assistance.

Example of application scenario:



FOX.SUM2 1+1=1 Class 1 5VA
FOX.SUM2 5+5=5 Class 1 5VA
FOX.SUM3 1+1+1=1 Class 1 5VA
FOX.SUM3 5+5+5=5 Class 1 5VA
FOX.SUM4 1+1+1+1=1 Class 1 5VA
FOX.SUM4 5+5+5+5=5 Class 1 5VA
FOX.SUM5 1+1+1+1+1=1 Class 1 5VA
FOX.SUM5 5+5+5+5+5=5 Class 1 5VA
FOX.SUM6 1+1+1+1+1+1=1 Class 1 5VA
FOX.SUM6 5+5+5+5+5+5=5 Class 1 5VA
FOX.SUM7 1+1+1+1+1+1+1=1 Class 1 5VA
FOX.SUM7 5+5+5+5+5+5+5=5 Class 1 5VA
FOX.SUM8 1+1+1+1+1+1+1+1=1 Class 1 5VA
FOX.SUM8 5+5+5+5+5+5+5+5=5 Class 1 5VA
FOX.SUM9 1+1+1+1+1+1+1+1+1=1 Class 1 5VA
FOX.SUM9 5+5+5+5+5+5+5+5+5=5 Class 1 5VA

The above is for balanced ratio inputs. For unbalanced ratio inputs please consult the sales office.


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