YORK YMC2 — VSD - INPUT CURRENT OVERLOAD

The display reads VSD - INPUT CURRENT OVERLOAD. The manuals print the message in this single wording, with no variants. It is listed among the safety shutdown messages of this chiller: the VSD has tripped on its input current and the chiller stays shut down until the fault is cleared.

VSD - INPUT CURRENT OVERLOAD is a safety shutdown generated by the VSD when its input current stays too high for too long. The drive monitors the highest of the three input RMS currents and compares it against 105% of the job input current at 90% line voltage; because the job input current setting is at nominal line voltage and the fault is based on power, and accounts for low-tolerance line voltage, the threshold works out to 105%/90% = 116.7%. The drive documentation describes the same value as 1.16 times the Input Job Full Load Amps value programmed at the Control Panel, never above the maximum for the given model of drive. The shutdown is generated only when the current remains greater than the overload value for 10 continuous seconds — a window provided to give the chiller time to unload.

• Input RMS current above the overload value: the highest of the three input RMS currents must stay greater than the overload value continuously for 10 seconds; that is the condition the manuals give for generating this shutdown.
• Power fluctuations: an additional 5% of current is built into the overload value specifically to reduce nuisance shutdowns due to power fluctuations, so sustained fluctuations that still hold the input current above the value for 10 seconds are the trigger situation the manual names.

• Overload value: 1.16 times the Input Job Full Load Amps value programmed at the Control Panel.
• Drive-model cap: the overload value must not exceed the maximum for the given model of drive — for example, 416 Amps for drive 0490 and 825 Amps for drive 0774; the maximums for the other drive models are 511, 650 and 1195 Amps.
• Percentage threshold: the highest of the three input RMS currents is compared against 105% of the job input current at 90% line voltage, i.e. 105%/90% = 116.7%.
• Line-voltage allowance: the calculation takes into account installations where the input line voltage could be up to 10% below the nominal value.
• Trip timer: the input current must be greater than the overload value for 10 continuous seconds before the shutdown is generated; the 10 s timer is reset if three consecutive RMS current values fall below the overload threshold.

The chiller does not restart by itself after this safety shutdown. Both manuals give the same instruction: When the condition clears, the chiller can be started after the CLEAR FAULTS button is pressed. The sequence is to let the overload condition clear, press the CLEAR FAULTS button, and then start the chiller.