YORK YK — FLTR HIGH TDD FLT

The panel shows FLTR HIGH TDD FLT. The manual prints the message in exactly this form, with no variants, among the VSD display messages for this chiller. It is described as a shutdown: the trip fires when the distortion condition described below is met.

Per the manual, this shutdown indicates that the filter is not operating correctly and the input current to the VSD/filter system is not sinusoidal. The measured quantity is TDD — Total Demand Distortion — which the IEEE Std 519-1992 standard defines as the total root - sum - square harmonic current distortion, in percent of the maximum demand load current (15 or 30 min demand). On the filter option supplied by York, the displayed TDD is the total RMS value of all harmonic current supplied by the power mains to the VSD system, divided by the job FLA of the VSD, expressed in percent.

• TDD exceeding 25% continuously for 45 seconds — the manual lists this as the one condition that produces the shutdown.
• For scale: the harmonic filter option was designed to hold the input current TDD of the VSD system at 8% or less, while a standard VSD without the optional filter typically runs at a TDD on the order of 28 - 30%.

• Trip point: TDD above 25%, sustained continuously for 45 seconds.
• Design level of the York harmonic filter option: input current TDD of 8% or less for the VSD system.
• Typical unfiltered level: a standard VSD without the optional filter shows an input current TDD on the order of 28 - 30%.
• How TDD is figured on this option: total RMS value of the harmonic current from the power mains to the VSD system, divided by the job FLA of the VSD, in percent; the IEEE Std 519-1992 definition it follows references a 15 or 30 min demand.