KB-2 Details on how the six(6) stage control works for a Q1 device

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The Q1 6 stage control has 3 types of staging control each with a stage rotation function. Each stage has an on/off delay and the entire set has minimum on and minimum off timer's. Any amount of stages between 1 and 6 can be set up and each stage can be used in an analog or digital configuration. The amount of stages will determine the amount of total control scale for each stage. Each stage will receive an equal amount of the total load. For instance if there are 4 stages, then each stage will control 25% of the total load. If a stage is configured as an analog type of control then the stage will cycle through a full 100% of it's value inside of the stages 25% control limit.

 

Example:

4 Stages

Total cooling load of 58%. Stage 1&2 are 100% (total load is above there limit). Stage 3 is 32% (8% past it's start limit of 50% and 32% of it's total scale). Stage 4 is 0%(OFF) because the total load has not reached it start point of 75%.

All stage control types have the availability to rotate the starting stage. Choosing this option will have the stage control keep track of the amount of time each stage has been ran and on start-up it will find the stage with the least amount of run-time and use that for it's starting stage. The stage number chosen for the start-up will be considered the 1st stage and the stage control will continue adding stages in a circular fashion. For instance if stage 3 was chosen for the start-up stage then stage 4 would be the 2nd stage, stage 1 would be the 3rd and stage 2 would be the 4th.

 

Minimum On Timer: This is the minimum amount of time a stage must be active before it is allowed to turn all stages off. The timer starts as soon as the stage control is activated. If more then 1 stage is being used then the timer will prevent the 1st stage from being turned off completely prior to this amount of time has passed since the command too turn the first stage on.

If the stage is configured to be a modulating or analog type of output then the 1st stage will sit at the minimum output amount (based on the minimum value from the PID loop).

If the minimum amount is 0% then the stage will hold the output value at 0.005% until the minimum on time has been achieved.

 

Minimum Off Timer: This is the minimum amount of time the stage control must stay in the off command before it is allowed to enable the 1st stage. Once the stage control is turned off this timer will continue to prevent the enabling of any stage until the timer has counted down to 0. The timer is started as soon as the stage control is deactivated.

 

Stage Delay: This is the amount of time a stage must be in demand contentiously in order for it to be activated. The timer is also used to stage down, so if the stage is active it must not be needed for this amount of time continuously in order for it to be shut-down.

If the stage is configured to be a modulating or analog type of output then the stage will sit at 0.005% until the delay time has been achieved.

This timer does not apply to the 1st stage of a multi-stage control, nor does it apply if there is only 1 stage of control.

 

Incremental Type Control: Incremental type control will add the next stage when the previous stage has reached its full amount and there is still a need for additional stages. As with the first example A total load of 58% with 4 stages of control will have stages 1 & 2 at 100% load then stage 3 will be at 32% load, or in the case of digital stages all 3 stages will be in the ON state. This type of control is useful for compressor or electric heater type staging for a DX unit.

 

Step Type Control: Step type control is similar to incremental however instead of each stage staying on after the next stage is applied it turns off the last stage as the next stage is turning on. With the same scenario applied the first 2 stages would be 0% and the 3rd stage would still be at 32% or in the case of digital stages only stage 3 would be in the ON state. This control is useful for relay logic, digital gas/steam valve's, or variable sized compressors.

 

Parallel Type Control: Parallel type control will keep all stages load equally, but only bring on additional staging only when the previous stages have been fully loaded. To keep with the same scenario, the end result of our 4 stages at 58% would have all 3 stages at 32% however the path to reach that loading would have had stage 1 run to 100% first, then when stage 2 came on it would have lowered the load of stage 1 to match the value of stage 2. Then when stage 3 was introduced, all 3 stage's are again lowered to match load of stage 3. This type of control is useful for a multi-staged compressor system with a variable digital scroll as 1 stage, also parallel pumps and fans.

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