Created Date: February 24,2012

Created by: milldrone

I'm trying to find a way to cool a 1hp 1800 RPM motor running at close to full load at 400 RPM?

Do they make an externally cooled 3P motor?

I'm going to be running a Hydraulic gear pump.

Because you are Saying "Do they make an externally cooled 3P motor? " I'm presuming that purchasing a new motor is "on the table " The simplest solution is to buy a TENV inverter duty motor. TENV = T otaly E nclosed N on V entilated, I know this sounds counter intutitive, (having a motor without active cooling), but these motors are made with premium insulating materials so that they can withstand 315 degree (at the windings) temperature without harm. The motor will get hot as in "sizzle spit hot " but it will not be damaged.

Your recent past questions along this line are along the lines of cutting costs, so I'm going to suggest this:. A muffin fan piggybacked to the fan end of the motor.

Created Date: February 24,2012

Created by: dieseltwitch

Because you are Saying "Do they make an externally cooled 3P motor? " I'm presuming that purchasing a new motor is "on the table " The simplest solution is to buy a TENV inverter duty motor. TENV = T otaly E nclosed N on V entilated, I know this sounds counter intutitive, (having a motor without active cooling), but these motors are made with premium insulating materials so that they can withstand 315 degree (at the windings) temperature without harm. The motor will get hot as in "sizzle spit hot " but it will not be damaged.

Your recent past questions along this line are along the lines of cutting costs, so I'm going to suggest this:. A muffin fan piggybacked to the fan end of the motor.

Yeah this is an R&D project into better ways of pumping for solar thermal applications. centi circulators are a pain in the butt and can quickly add up to 1000$ just trying to meet head pressures. I 've been working with a old gear pump I found and have quickly come to realize that a gear pump is a far more efficient and cost effective way of pumping at a steady rate where high head pressures and variable head pressures are involved. Solar thermal doesn't require much flow but some times a collector will produce a steam pocket and small circulators can't push through it and the system quickly over heats and blows off. where a gear pump will push relatively the same amount of fluid at almost any head. I'm just trying to find a pump that meets the needs. I found pumps for a good price. just need to make sure that pumping at slow speeds won't damage the motor.

Thats a good idea on the motor, I never though that a TENV would be better. your right. thank you...

And money saving is always ONE of the goals. but quality is first. thats why I'm always trying to find a more cost effective way or doing something with out compromising quality.

Created Date: February 24,2012

Created by: dieseltwitch

While a gear box is a good idea for something that need a constant flow. but solar thermal benefits best from variable speed applications. monitoring the temperature rise across the collectors and adjusting the flow to keep it at a target. while this isn't so critical in small system larger one benefit greatly from it. Sometimes I need to pump at 1 GPM and other I need almost 10 GPM.

with this pump I can do that but 1 GPM is at 200 RPM's... while 10 GPM is at 1700 RPM Thats why I love VFD's but finding a motor that can take it is proving to be the hard part. i found one on Baldors drill down but its 670$ for a 1 HP and their "true vector motors are $1,600 and up! I thought about using an SSR to do a kind of PWM that I got to work well with standard circulators but when you induce large torque loads it falls on its knees.

Created Date: February 24,2012

Created by: jwbaker3

We normally use a vector duty motor that have a separate fan powered by an external power supply. TEBC (totally enclosed blower cooled vector duty with a 1000:1 torque speed turn-down ratio or better)(we setup the drive to turn the blower on and off) But they are larger motors 143 frame and larger. If we have a motor in the hp you are using the TENV will work fine if it is vector/inverter duty with a large torque speed turn-down ratio. We have also mounted a pancake fan on the back of the motor to cool the motor. We prefer the motor have some cooling air at that low speed. You will also want to think about the torque/hp the motor will put out at 13 to 15 hz, a general purpose premium efficient TEFC/ODP/TENV normally have a turn-down torque speed rating of 20:1 and some are lower than that.

When I set up a system like yours we try to set up the motor to overspeed (above 60 hz) a 1800 rpm motor can safely run 3600 rpm (120 hz) you have to watch the torque as it drops quite fast above 90hz. We would try to run the motor between 90hz and 40 hz that will give you the 1500 rpm range you need without effecting the cooling on the motor very much and the motor will have good torque.(ether use a 6:1 gearbox or resize the pump) The motor will run about 2700 rpm at 90 hz and 1200 rpm at 40 hz. Most TEFC (totally enclosed fan cooled) motors have the same fan for a 1200 rpm and a 1800 rpm.

JW