Post a reply to the thread: Commander SK Variable frequency Drive for boiler single Phase
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It appears that the new model PMC board eliminates the drive altogether and sends the 0 to 10 Volt signal directly to the Blower motor's electronics the drive is a Commander SK Strangely enough the Benchmark 1.5 does not have an O2 sensor It varies the speed based on the air valve position and it has a combustion air intake temperature sensor the regulates a voltage input to the "T4" /analog in 2 port on the SK Drive terminal on the SK Drive It seems that this sensor will "Bias" the Drive's output as the temperature increases the air is less dense and more air is needed as the air cools it is More dense and less air/Slower speed is required Commander SK Model # SK B 1100075 a new problem with the identical drive on another unit no matter what I do i cannot prevent the driver from out putting the maximum frequency output regardless of how ,and how many times I adjust Parameter #2 "maximum speed (HZ) I do not want the drive to exceed 34 HZ regardless if it receives a speed input signal of 100%
What is the model and serial number? The only VFD I can find listed in any 120VAC model parts list and wiring diagram is a Vacuum Fluorescent Display which is part of the C More controller. The C More control sends a signal through the IO module and to the 0-10VDC input of either the motor or a drive depending on BTU output of the boiler and is drawn on their diagrams that I have looked at. This may not be the same on your boiler. J3 terminals 7, 8 at the IO module and the 24 pin connector 23, 24 on the control board. Without model and serial the rest is guessing.
Originally Posted by hvac69 What is the model number of the one you are working on? You may be looking at two different sets of literature for two different models. The larger BTU models have VFDs and the smaller ones have ECM motors from what I remember. Either way it is a 0-10VDC command from the control board to either the drive or the motor. This definetely has a Commander SK Drive The drawing shows that The boiler,"C More" board sends an analog Speed signal to the Drive The drive only sends an Analog output Signal to the actual blower motor I am guessing that the speed is varied with the O2 levels Why not have the boiler controls directly control the motor speed This motor has only four leads Two for power which are controlled by An onboard relay And two for the analog speed signal
What is the model number of the one you are working on? You may be looking at two different sets of literature for two different models. The larger BTU models have VFDs and the smaller ones have ECM motors from what I remember. Either way it is a 0-10VDC command from the control board to either the drive or the motor.
It has a USB stick in front of it don't remove it , it can cause problems
Its likely done thru a modbus serial command
Commander SK Variable frequency Drive for boiler single Phase Have an Aerco Benchmark Boiler which is rated at 120 Volts Single phase The Aerco Benchmark manual only states the the The furnace Inducer blower motor / single phase 120 Volts / fractional H.P. with four leads attached, two for the 120 Volts power Two for the 0 to 10 Volt D.C. Speed signal is fed its speed control signal From an Emerson Commander SK V.F.D. It does not show How the Boiler control board sends a signal to the V.F.D nor THE V.F.D wiring diagram the Emerson site list them as controlling Three phase motors Any info would be helpful
Commander SK Variable frequency Drive for boiler single Phase
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