YORK YK — VSD - Initialization failed

The display shows VSD - Initialization failed. The manuals print the message in this single form only. It belongs to the group of medium voltage variable speed drive cycling fault messages of the YK, and it is shown by the control panel when initialization with the drive — the MVVSD — has not been successful.

The message means that initialization between the control panel and the MVVSD was unsuccessful, or that the drive failed the operational check it performs when a run signal is received. Three conditions produce it: the control panel could not establish serial communications with the MVVSD, the MVVSD did not deliver valid Hp and voltage codes, or the DC current transformers monitoring the current flow to the motor were found not operational. In every case the consequence is the same: the system cannot start and a cycling shutdown is initiated.

• Serial communications not established. After power has been applied to the system, the control panel attempts to establish communications with the MVVSD through the serial communications link and tries 10 times during initialization. If these attempts are unsuccessful, the control panel prohibits a system start and initiates a cycling shutdown.
• Hp and voltage codes missing or invalid. During initialization the MVVSD transmits Hp and voltage codes to the control panel; these provide the Hp and input voltage ratings shown for display purposes. If valid Hp and voltage codes are not received upon initialization, the control panel prohibits a system start and initiates a cycling shutdown.
• DC current transformers not operational. When a run signal is received from the control panel, the drive performs an operational check of the DC current transformers monitoring the current flow to the motor. If the drive determines that the transformers are not operational, the system cannot start and a cycling shutdown is initiated.

1. Note at which point the message appears: after power has been applied to the system and during initialization, or at the moment a start is requested and the run signal is issued to the drive.
2. If the message appears during initialization, the unsuccessful exchange between the control panel and the MVVSD is the reason — either the serial communications link, which the control panel tries 10 times, or the Hp and voltage codes the MVVSD transmits so the panel can show the Hp and input voltage ratings.
3. If the message appears when a run signal is received, the drive's operational check has found the DC current transformers monitoring the current flow to the motor not operational.

No manual reset is described for this message. Messages automatically clear when the fault condition no longer exists; if the chiller was running when the fault occurred, it automatically restarts. Until the condition clears, the system cannot start.