7.9 REMOTE LOAD/UNLOAD
The remote load/unload option gives the operator the ability to control the loading and unloading of the compressor. This option is enabled when two switches are wired to the Intellisys to perform this function. The firstswitch is the master/local input (P3, 25 & 26) and the second switch is the load/unload input (P3, 27 & 28). If the master/local switch is closed, the Intellisys will read the load/unload switch for loading and unloading the compressor. If the load/unload switch is closed, the Intellisys will load the compressor.
If the load/unload switch is open, the Intellisys will unload the compressor. If the master/local switch is open, the Intellisys will ignore the load/unload switch and operate the compressor normally.
7.10 MODBUS
The Modbus option uses the Modbus protocol and modbus address set points in the OPTIONS menu. This is used by the
7.11 INTEGRAL SEQUENCING
Integral sequencing allows one compressor, the lead, to sequence up to 3 other compressors. The compressors are daisy chained together using port P8 on the Intellisys. Each compressor has a unique address and the lead compressor will sequence the other units in numerical order based on that address.
The lead compressor will be the first to load and the last to unload. It is also the only compressor that can modulate. If the lead compressor’s mode of operation is Mod/ACS or Modulation Only, it will modulate when it is loaded. Once loaded, if pressure falls to its online set point, the lead compressor will transmit a load command to the next compressor in sequence. The lead compressor will then wait for a period of time for the line pressure to rise. This time period is determined by the load delay time set point. At the end of this time period, if line pressure is not rising, the lead compressor will transmit a load command to the next compressor in sequence. This will be repeated until the line pressure starts to rise.
When line pressure rises to the lead compressor’s offline set point, it will transmit an unload command to the last loaded compressor in the sequence. The lead compressor will do this every 10 seconds until the line pressure starts to fall.
After a certain amount of time or at a certain time, the lead compressor can change the sequence by transferring the lead to the next compressor in the sequence. If the set point, Lead Change - Hours, is set to a value greater than 0, the unit will operate as the lead compressor for that number of hours before transferring the lead. If Lead Change - Hours is set to 0, the set points Lead Change - Day and Lead Change - Time will be used to determine when the lead will be transferred. The Lead Change - Day set point will contain the day of the week the lead will be transferred. The time of the day will be contained in the Lead Change - Time set point. The lead will be transferred when the real time clock matches these 2 set points.
To connect the compressors for integral sequencing put the 4 position connector into port P8. One connector,
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