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CT (Current Transducer) Fault

Description of Fault

A CATALYST CT Fault is generated when the unit power is less than the fan or drive power.

On a drive unit, the CT is on the full unit power and the drive is only monitoring the fan power. Therefore, the CT must be at least equal to the fan power.

On a non-drive unit, a CT fault can reflect extraordinarily high amp readings (250A or higher) based on CT jumper position.

A CATALYST CT Fault will automatically reset when…


Possible Causes

A CATALYST CT Fault is typically caused by:

  • Being on the wrong leg of power (drive units).

  • CT wired incorrectly.



eIQ Platform

  1. Run an economizer test on the soft service switch.

    1. If the fan power is higher than the unit power, then dispatch a technician.

  2. Run a cooling test on the soft service switch.

    1. If the power does not increase, then dispatch a technician.



  1. Check the amp measurements. Make sure the CT is on the high leg.

  2. Verify the wiring on the CT.

  3. Compare amp measurement with the readout on the eIQ Platform.

    1. If they are not equal, verify the jumper positions on the CT. See the following chart:

          Unit Voltage          Unit Size           CT Size            CT Jumper Setting

                            No Drive                        50 Amp           50 Amp

          208/230V              ≤ 20 tons          250 Amp         100 Amp

          208/230V              ≥ 25 tons          250 Amp         250 Amp

          460V                      ≤ 40 tons          250 Amp         100 Amp

         460V                      ≥ 50 tons          250 Amp         250 Amp


  1. Measure the DC volts off the CT. Does the measurement match the meter on the high leg?

    1. All output is zero to 10 volts DC.

      1. On a 50 amp CT, 10 V is 50 A and 5 V is 25 A.

      2. On a 100 amp CT, 10V is 100 A and 5 V is 50 A.

      3. On a 250 amp CT, 10V is 250A and 5V is 125A.

  2. If the values do match, then there may be a faulty CT.

  3. If these values do not match, contact Transformative Wave for further assistance at or (855) 867-2333.

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