Welcome back to Teaching the Unteachables where we dive into teaching and learning
methodologies for professionals like you. This episode brought to you by Regal
Rexnord Gentec Motors, the leading brand in electronically commutated motor
technology. Learn more at regalrexnord.com.
All right well hello once again thank you all for joining Did You Know? Last
month we had the opportunity to hang out with Chris Mohally from Regal Rexnord.
Chris how you doing today again? Doing great, happy holidays. Absolutely getting
real close, getting excited, getting busy, ready for a break. Ready for the break.
Oh my goodness, absolutely. So we spent a lot of time talking about ECM constant
airflow, our true variable speed ECM motors, and they are quickly gaining
popularity in the industry. But they're not the most popular ECM motor out there,
at least what I see out in the field. So today we're going to be spending some
time with the Constant Airflows cousin, Constant Torque. Very similar but boy
they have some different command controls. So Chris thank you so much for
joining us and for those that missed last month's show it is out there. We got
the live version of it plus we've got the finished edited version as well on
our YouTube channel s2institute HVAC excellence so make sure to go check that
out if you missed that one and let's go ahead and dive on into this thing and
let's talk a little bit about Constant Torque ECM motors. Sounds good. We'll
start right in with what you said there Constant Torque ECM and their
applications. So last time we talked about Constant Airflow motors and
they're more applicable to the premium level HVAC systems. Constant Torque
motors are more applicable to the mid-tier and lower tier systems but as
you're going to learn there's some characteristics that cross over which I
think the audience might find kind of interesting. These are multi-tap motors
majority of them are multi-tap motors. I have to remember to change my
teaching habits because the motors have changed in the last five years or so.
Exactly. The majority of them are multi-tap motors very similar to a PSC
motor where if you want the motor to operate more or less airflow you simply
move to a higher or a lower tap value and they're also Constant Torque as you
already mentioned and as we did last time we will delve into what Constant
Torque really means and especially what it means to airflow. These motors do
perform very similar to a PSC motor but we'll show exactly how similar and what
that means as far as making airflow selections and diagnosing airflow
performance issues. Yeah absolutely. So what does multi-tap mean? I'm pretty sure
it's you know what I've said already. Yeah. Fairly plain but you know just just to make sure.
Manual selections that's really what we're talking about. It really is so
you know really the main difference between a Constant Torque ECM and a PSC
motor is they both have speed taps and it's funny because we we we call them
speed taps but even on a PSC motor they were never speed taps you know you
when a PSC motor when you want to make it multi-speed you tap the winding in
multiple places right and each tap gives you a different amount of torque each
different amount of torque is going to give you a different amount of speed
based on the load. Probably went a little too deep there but so these things. No, makes sense to me.
We call these speed taps but really each tap has a programmed level of torque and
that level could be either a percent of maximum torque or an actual ounce feet
of torque that you know again if I go to a higher torque level I'm going to get
more airflow a lower torque level I'm going to get less airflow but I'll
default and go back to what the industry is comfortable with and we'll just call
them speed taps. And they do they look very similar I mean when we're talking
about PSC motors we had typically wires that were our selection but on some of
our manufacturers we actually had plugs or sockets on the motor that was the tap
selection. Yeah so when we look at our ECM constant torques now we're going to
see a similar type of plug and so a lot of people are familiar with
that particular look you know when we're getting to the actual socket we're gonna
go oh wow all right that's starting to look a little bit familiar to us right
well what do they mean you know what are we doing with each one of these taps? So
the main difference here again being an ECM is we provide line voltage to the
motor continuously you've got LGN line ground neutral the N is stamped on all
of our plugs whether it's a 115 volt 230 volt 277 or 460 volt it's always
stamped as N so the N changes meaning whether you're in a 115 volt motor it is
actually neutral a 230 volt motor it's going to be L2 and so on and then the C
of course is common so like the constant airflow motors we discussed last time
around this motor is powered continuously with line voltage and it is
the low voltage in this case 24 volts AC that actually energizes the speed taps
tells the motor not only when to turn on but the tap that's energized tells the
motor which torque level to operate at so the only other thing that I do want
to cover make sure I cover at least once I'm sure I'll say it again because I
often repeat myself is on the OEM motors you know these speed taps are programmed
so the manufacturer of the appliance gets to program the torque value that
goes into each one of those taps and that's where as we discussed later you
know these these motors look very simple at the onset but then they can get a
little bit more complex when you understand that every OEM can program
them differently so they you know so tap one may not always be low speed and
yeah tap five may not always be high speed as just as an example yeah now
I've ran into that before where they were you know opposing actually had some
that came from a manufacturer one time as a warranty replacement motor and I
got some calls from the field hey these are not running at the correct speed
then what do you mean right like low is high and high is low and I cool that
could be an issue yep exactly so you know the best recommendation I can give
technicians is to really treat these motors just like you did a PSC motor go
go to the door schematic or the unit manual where you'll find either the color
chart like we did for PSC motors right or in this case the number chart that
tells you what you know each number represents as far as high medium low
speed or other some manufacturers will actually label them as the heat tap or
the cool tap or you know electric strip heat or something like that and of
course we'll have to confer with those manuals for our airflow because it's a
constant torque motor it does not maintain airflow like the constant air
flow motor and of course we'll get into that in a little bit so let's let's dive
right into you know what makes the motor so different so yeah almost all constant
torque motors built by us and our competitors use this same and I like to
use the word standard nine terminal block okay CLGN 12345 it comes up to nine you
got a you got a blank in the upper corner next to N so I call it a standard
nine terminal block and so it us in the competition build our motors with the
same block almost all of them are using 24 volts AC to energize the speed taps
so what makes them what makes them different if you look at the diagram
that's on the screen we see and I'm using examples of how different
manufacturers programmed the motors this one programs the motor with tap one as
low speed and tap five is high speed just like with a PSC motor if I needed my IC
heat is connected to tap three so if I wanted to increase my heating airflow I
would move the heat tap from three to four and I would get more airflow very
simple so I'll give you another example and if you didn't pay attention I'll
tell you what changed here like a where's Waldo tap three didn't change
yeah but but everything else did tap five is now low speed and tap one is now
high speed and to your point if a technician is not paying attention to
the speed taps they may move them in the wrong direction which you know obviously
you can probably figure out if your amperage goes down and your airflow
goes down I probably went in the wrong wrong direction you can go the other way
but you know it's just as easy to reference the schematic and know what
you're talking about when you're working on the unit right this next one is going
to give you even more reason to focus on that unit schematic so and this is this
is actually fairly common in single stage package units that you constant
torque motors because of saying and especially if they're all electric so an
all-electric single stage package unit might use one speed for AC and electric
strip heat pump AC heat pump heat and heat pump or and electric strip you know
I may use one speed for everything and if it does you know it's comes factory
wired to that one speed now there's actually a high speed that I can choose
here but the the the key to this diagram is there are three taps on this motor
that are not programmed they have no functionality so if I put 24 volts on
tap three yeah the motor is not gonna run okay absolutely that makes sense so
it depends on how it was programmed from the manufacturer no program no run
absolutely so if I'm used to working on systems that look more like the previous
one or you know preview either either one I might think that going up to tap
three is gonna give me more airflow the motor shuts off and then I'm wondering
well do I have a bad motor because I don't know enough about constant torque
motor so this is really more probably more important for diagnostics but also
important for that technique technician that shows up on the job they've got a
frozen coil or a trip limit and they move to it inadvertently again package
systems common split systems very uncommon to have unprogrammed taps but
they inadvertently move to a tap that has no program in it motor shuts off I
mean I myself if I didn't know better would think yeah something wrong with the
motor that motor that would be the call that would come right right that's not
working so that is a fantastic if we get anything from this entire program that
is some super good information all right so here's another example and this is
pretty common in air handlers from one manufacturer I'm not gonna say who the
manufacturer is you see a low medium and high and you know if a manufacturer
programs all five whether they program tap one is low or tap tap one is high you
know tap three stays the same it's medium and you might start getting the
mentality that well the middle of the motor is always going to be medium well
that's not the case if you look at this particular handler where they did low
medium and high and one two and three and then they put tap four as the
dedicated electric strip tap and then see manual for tap five which my joke is in
class so is always well that taps never gonna get used because the manual is
never gonna be left yeah they actually open the manual to read this one and
know what it is not picking on the technician that's currently on the job
but not a lot of manuals stay on the job site exactly we're talking to the
technicians that don't read manuals we're just encouraging them everybody
else does and we're so glad that you do that so this is my cue to throw out the
RTF and read the whole manual manual man those are some examples of the most
widely format that constant torque motors are used in all the five taps
are 24 volts AC activated the 24 volts AC turns the motor on it the tap
selection determines how much torque it puts out the manufacturer that programmed
the motor tells you if it's low medium high speed and away you go very very
simple motor funny that you mentioned earlier you know PSC motors having
terminal blocks in the past five ten years there's another competitor of mine
that puts out a constant torque motor that looks like a PSC motor looks like a
PSC replacement that's actually and I'm sorry for boys pointing that way I've
got a no that's right that is actually a constant torque motor with just leads no
plumber sure it has the same line ground neutral common still a square the same
way as we assume five 24 volt wires for its speed tap so very very similar and
also very widely used by by one manufacturer yeah we we put out a new
motor recently called the n site motor where we changed the plugs which we went
from the standard nine terminal plug to two different plugs and that was
released primarily in 115 volt motors for the fossil fuel market so I'll talk
about that in a little bit and then there's also two not now two
communicated modes for constant torque motors one of those communicated modes
is called PWM and one is called nine speed men technicians that you know are
paying attention to the manuals or the schematics are probably already seeing
these because they've been out for quite a while but I'm starting to get I do
tech support for us so I'm starting to get more and more questions on these so
I'm recognizing that the awareness has has grown on these motors you know
manufacturers will take one of our motors a technology that's new to the
industry they'll use it and it'll take technicians a while to actually notice
that something something different in the appliance so yeah these have been
around for a while and I'll talk about that when we get to them sure but that's
that so that's the evolution of constant torque in one in one screen in the nutshell
yeah again 90 plus percent of what's out there is that standard nine terminal
with the 24 volt speed taps you've got some still using wires only and then
you've got a couple of new with new terminals and PWM and nine speed so
let's dive right into unless you had something to add one little question so
yeah good question came in from Ray about you know so how do you get the
correct programmed motor for your application one you go with the OEM
motor or you go with a replacement motor and you verify what your CFM ratings
were on your OEM motor and then you just look on your new motor I could be wrong
but that's the experience that I've had with replacement motors how would regal
how would gentech approach that one yep no you said it perfectly if you want the
exact motor that came out you would have to go back to the manufacturer of that
appliance order it from their authorized distributor by the model number of the
appliance to get the program motor that came out of it but we do make generic
motors that have all five taps programmed and it's very just like with
replacing a OEM PSC motor with a generic PSC motor we can replace an OEM constant
torque motor with a generic constant torque motor that has five speeds yeah
and as you said I'm going to adjust my speeds until I get the correct airflow
I you know so since it came up now and we'll it'll come up later again okay you
know so I often get asked well I like to go back with OEM motors because then I
know all I have to do is plug it in and I'm done I don't have to measure airflow
because you know I put the OEM motor back in and my my contest for that is
well what if the when the system was first installed what if no one ever
measured airflow and adjusted the speeds to set it up properly on day one and
then I get the well and the gosh-golly and the kick in the rocks and then I
take it a step further and say now I'm really gonna blow your mind these are
constant torque motors what if the static pressure today is different than
the static pressure that was on day one even if it was set up properly if my
static pressure is different today than my air flows different today and I still
have to measure airflow so bottom line is you're gonna have to measure airflow
whether you're putting the OEM motor back in or universal motor back in so
really putting a universal motor back in isn't any more time than putting the OEM
motor back in as long as you're following industry best practice yeah
absolutely you know Jason Objute from our team says this all the time he says
compressors don't die they're murdered and it's kind of the same way with ECM
motors ECM motors don't typically die on their own it takes a lot to kill one but
boy they can easily be murdered if they're not set up properly and they have
too much static pressure and I would agree with that wholeheartedly yes sir so
we'll we'll move on to the first variation if you will which is what we
call the N-site motor again we launched this in 2019 with the 2019 fan
efficiency regulation change 115 volt only but we you know it has two
different plugs but if you look at it really closely it's the same motor as
what you're used to it you know you got the nine terminal plug here and I'm
marrying it up to the the three the three terminal plug for line voltage and
the terminal plug for low voltage different configuration but yeah all
there and and so you're probably only gonna see this if you're a technician
in a fossil fuel market because we won't today we only make it in 115 volt
applications yep and which means it's you know it's it's fairly new to the
industry as well because it's only about three years old well almost four years
old now right coming up on its birthday getting close there you go and this
motor is by the way also capable of the 24 volt speed taps and also the PWM that
we're gonna talk about in just in just a minute okay just a minute how about next
when I'm leading in myself that's perfect PWM and if you're not familiar
with with the acronym it stands for pulse width modulation and all it is is
a it's a DC duty cycle if I speed up the duty cycle I'm asking the motor to
operate at a higher torque value if I slow down the duty cycle I'm asking the
motor to operate at a slower duty cycle so from a really fundamental standpoint
if I if I think about the old Rhea stats you know I turn them I turn them up and
the motor goes faster or the light gets brighter I turn them down and the motor
gets slower go slower or the light gets dimmer with PWM the OEM board has full
control over the motor whatever if they send a really low PWM signal they'll get
a really low output out of the motor if they send the highest if you know 100%
PWM signal they're gonna get maximum output of the motor so they they
literally have infinite speed control the motor in PWM one thing that
technicians can you know because again the manual is not often on the site the
schematic may not specifically spell out this is PWM but one thing that
technicians can note it will notice and when the constant torque motors used in
PWM is tap one and terminal C or sorry terminal one and terminal C are going to
be typically wired back to the board through a plug on all of our 24 volt
motors there the motor terminals are going back to heat taps cool taps fan
taps and if they're all wired you know park or unused taps but in the case of
PWM what they're gonna find is it's not going back to a heat or cool a fan it's
just it's going to be going back to a dedicated plug because you're not meant
to adjust that tap you're meant to leave that alone I don't want to put 24 volts
AC on that thing no and it's not going to be 24 volt AC the PWM signal is
created with DC voltage so you'll have to again go into the manufacturer's
manual to find out what that DC voltage is that relates to the PWM signal and I
that signal determines the motor torque also determine at which determines the
motors output so on a PWM controlled motor you're going to adjust your airflow
with the dip switches so you're you know here so here we are we talked about
constant airflow last time around and how everything is going to be set up
with either dip switches or jumper pins or you know today's communicating
thermostats I'm going to go in and I'm going to adjust the menu selection now
here we are with constant torque motors and they're right back to that form of
you know we use PWM communication and constant airflow as well and now we've
got constant torque motors using PWM and being controlled by the dip switches on
the board and you're going to be at the National HVACR education conference this
year is that correct? I will I'll be teaching a class and I will have a booth there to answer any questions you have.
And bring your books with you if you want to get the book signed by the
author I would love that if you bring a book with you we'll make sure that we
have a book signing of authors while we're there. So hopefully see you all at the
National HVACR education conference and we hope that you all come back next week
and hang out with us and next month we're going to be back again with Chris
we're going to be talking about ECM condenser fan motors and the following
month we're going to actually dive into some more characteristics of ECMs with
airflow and maybe we'll tear some motors apart and dive a little deeper so you
have some ECM questions get them prepared and Chris thank you so much for
hanging out with us once again I enjoy diving into ECM motors and getting a
better understanding of these newer technologies. Probably more fun than it
should be. I love it when I get the calls I had so much fun on your show.
You had fun talking about motors. I look forward to these shows.
Alright well I think we're gonna call it a wrap we really appreciate everyone
hanging in as long as you have I know it's a lot of information and we really
enjoy hanging out with you and being a part of this HVACR building science
community and Chris Mahaly we will see you in a few weeks. Sounds good I know it
dates the show but happy holidays to you and your families everyone. Absolutely
everyone thank you so much we'll see you later. Bye.