Discover our Clipsal Smart Home packages as seen on the Block

in location

OR

I'm looking for

  • Wholesalers
    • Uncheck All Check All
  • EXPERTISE
    • Expand
    • Expand
    • Expand
    • Uncheck All Check All
  • Switchboard Manufacturers
    • Uncheck All Check All
OR

The best way to see what Clipsal electric products can do for your home is seeing them in action at a Clipsal Display Centre.

Product stock may vary according to location. If you're after a specific product range, please check with your chosen location before visiting.

10 Results
    Load More Load Complete
    Change Location

    Putting CTs in Parallel - multiple CTs on one port

    Issue
    A single meter is required to monitor multiple loads. 

    Product Line
    ION Meters
    PowerLogic Meters

    Environment
    3090SCCTs

    Resolution
    *Warning: Installation and maintenance of this device should only be performed by qualified, competent personnel that have appropriate training and experience with high voltage and current devices. Failure to follow the instructions / warnings in the Meter Installation Guide can result in permanent damage to the meter, severe injury or death.


    Two or more CTs can be landed on a single port of an ION or PowerLogic meters, provided the following is considered:

    *Putting CTs in parallel:

    1. All of the transformers (CTs) must have the same nominal ratio, regardless of the rating of the circuits in which they are connected.
    2. All transformers which have their secondary leads in parallel must be connected in the same phase of the primary circuits.
    3. The secondary leads must be paralleled at the meter and not at the current transformer.
    4. There should be only one ground on the secondary side of all transformers at their common point at the meter.
    5. Use modern current transformers with low exciting currents and, therefore, little shunting effect when one or more current transformers are floating at no load. (Three of more floating current transformers might have an effect that should be investigated).
    6. The secondary circuits must be designed so that the maximum possible burden on any transformer will not exceed its rating. The burden should be kept as low as possible as its effects are increased in direct proportion to the square of the total secondary current.
    7. A Common voltage must be available for the meter. This condition is met if the circuits share a common bus that is normally operated with closed bus ties.
    8. Burdens and accuracies must be carefully calculated.
    9. If adjustments are made at the meter to compensate for ration and phase angle errors, the ratio and phase angle error corrections used must represent the entire combination of transformers connected as a unit.
    10. The watt hour meters must be of sufficient current capacity to carry without overload errors the combined currents from all the transformers to which it is connected.
    11. Low-voltage, low-burden-capability current transformers are not suited to this application since the burden imposed on parallel secondary may be very high.
    12. Meter voltage usually is equipped with a throw-over relay to avoid loss of meter voltage in the event the normal supply is de-energized.

    *Figure 1.0: Multiple CTs connected to a single port on a ION Meter.

     

    More Information

    Source for 1-12 list and Figure 1.0 below:

    *Source: [Handbook for Electricity Metering, 10th edition: Edison Electric Institute - Pg. 274, 2002, Washington, DC]

    Didn’t find what you were looking for?

    Try Searching Again View Our Categories

    Need further assistance?

    Our Customer Care department provides total customer service solutions for our residential, industrial and commercial applications.

    Get Assistance