Current Transformers
Split Core vs. Solid
Should I order split core or solid core CT's? What's the difference?
Solid Core
Solid core Current Transformers (CTs) look like donuts with wires attached. These ring-shaped devices slip over the power lines and measure the electrical current flowing through the line. The CT "secondary" wires connect to the meter, facilitating power and energy calculations.
Solid core CTs are very accurate (0.3% maximum error), small in size, and inexpensive. However, power must be turned off and the circuit opened, generally at a circuit breaker, so that the solid core CT can be slipped over the power line. After installation the power wire must be reconnected to close the electrical circuit. Installation usually only takes a minute or two per CT.
Split Core
Split core CTs can be taken apart, or ‘split' into halves, which negates the need to turn power off and open the circuit during installation. This saves a little installation time, and for critical loads that cannot be switched off, split core CTs are a must. However, split core CTs are more expensive, bulkier, and not as accurate as solid core CTs.