YORK YMC2 — VSD - PHASE A INPUT GATE DRIVER

The control center shows VSD - PHASE A INPUT GATE DRIVER. Both manuals print the message in exactly this capitalisation, and no other variant is given for this model. It belongs to the YMC2's group of cycling shutdown messages. The manual's sample screen shows the message on the System Run summary display, directly under the SYSTEM RUN header.

The VSD feeds itself through a rectifier — the fault tables call it the boost rectifier, and the gate driver description calls it the input rectifier. The rectifier's IGBTs are switched by gate driver boards. On Phase A, those boards monitor their power-supply voltages within the gate driver circuit, as well as the saturation voltage drop across each main IGBT while it is turned on; this monitoring is how the drive verifies that the input rectifier can be properly controlled. When a voltage on the Phase A boost rectifier IGBT gate driver board falls out of the prescribed limit — in other words, when the gate driver monitor determines that the input rectifier cannot be properly controlled — the board turns the rectifier's IGBTs off and the drive shuts down, displaying this message.

• A monitored power-supply voltage on the Phase A boost rectifier IGBT gate driver board fell out of its prescribed limit.
• The gate driver monitor determined that the input rectifier cannot be properly controlled; the monitoring behind this covers the power supplies within the gate driver circuit and the saturation voltage drop across each main IGBT while turned on.

The manuals give no reset procedure for this message, and none is needed: The chiller will automatically restart when the cycling condition clears. Once the condition the gate driver monitor saw has cleared, the unit returns to operation on its own.