York YCAS0130 manual Micro Panel Contents, Remote Start/Stop, Remote Current Reset

Micro Panel Contents

1.10EMS/BAS CONTROLS

The microprocessor system can accept remote signals to Start/Stop the chiller, adjust maximum allowable run- ning current for each compressor, and adjust the chilled liquid leaving temperature setpoint. These functions can easily be controlled by connecting user supplied “dry” contacts to terminals in the control panel.

Remote Start/Stop

Remote Start/Stop can be accomplished using a time clock, manual contact or other “dry” contact in series with the flow switch which is connected to Terminals 13 and 14 in the logic section of the control panel. The contact must be closed to allow the chiller to run. Any time this contact opens, the chiller will shut down and the NO RUN PERM message will be displayed. The location of the flow switch connection is shown in Sec- tion 1.12.

Never bypass a flow switch. This will cause damage to the chiller and void any warranties.

Wiring from remote “dry” contacts (for stop/start and reset functions) should not exceed 25 ft. (8 m) and should be run in grounded conduit that does not carry any wiring other than control wiring or shielded cable. If an inductive device (relay, contactor) is supplying these contacts, the coil of the device must be suppressed with a suppressor YORK Part Number 031- 00808-000 across the inductive coil.

Remote Current Reset

The maximum allowable running current for each com- pressor can be adjusted remotely to a lower value using repeated timed closure of “dry” contacts connected to Terminals 13 and 16 located in the logic section of the control panel (See Section 1.12). The duration of the contact closure will determine the amount of adjustment. Generally, this input is used for purposes of demand limit and operates as follows:

FORM 201.19-NM1 (204)

Closing the input contact for a defined period of time allows reset of the % Current Limit downward. Contact closure of 1 - 11 seconds will allow % Current Limiting to be adjusted downward from 105% by a maximum of 75%, i.e. to a minimum value of 30% FLA. EMS Current Limiting operates independently of the High Average Current Unload (See Section 8.2). The micro will always look at the two Current Limit Setpoints and choose the lower as the controlling value, whenever Remote Current Limiting is utilized. Contact closures of less than 1 second will be ignored. A closure of 11 seconds is the maximum allowable closure and provides a Current Limit reduction of 75%. The remote reset cur- rent can be calculated as follows:

REMOTE

RESET = 105% FLA - {(Contact Closed Time -1sec) x (75% FLA)}

CURRENT 10 sec

For example, after a 4 second pulse, the offset would equal:

Remote Reset Curr = 105% FLA - {(4sec - 1 sec) X (75%FLA)} 10 sec

=105% - 225%FLA sec

10 sec

=82.5% FLA

To maintain a given offset, the contact closure signal must be repeated (refreshed) every 30 seconds - 30 minutes. The refresh is not accerted sooner than 30 seconds from the end of the last PWM signal, but must be refreshed before 30 minutes has elapsed. After 30 minutes, if no refresh is provided, the setpoint will change back to its original value.

After an offset signal, the new Remote Current Limit may be viewed on the EMS current Limiting Display under the Motor Current Key (see Section 3.5). However, if this display is being viewed when the reset pulse occurs, the setpoint will not change on the display. To view the new offset, first press any other display key on the keypad and then press the Motor Current Key.

Remote EMS Reset will not operate when a Remote Control Center Op- tion Kit is connected to the micro. The Remote Control Center will always determine the setpoint.

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