double yaskawa's drives at 100%

[Airchucker]

double yaskawa drives at 100% for weeks now. How long will they last?

[John Culpepper]

I've got a pair of Honeywell 125 hp running four 60 hp blower motors. During the summer they will run at 100% for weeks at a time. They are 2 1/2 years old and are running great. Just keep the drives cool and clean and you should be fine.

[Airchucker]

Moved into new building 3 weeks ago. Responsible for the building maintenance. The drives have been at 100% entire time. Cool in Ga., Economizer running as expected, but concerned about these drives running wide open with no sign of backing off. they serve 25 VAV's. Sup and ret drives.

[John Culpepper]

How are the drives controlled? Mine are controlled with a static pressure switch about 2/3 to 3/4 of the way down the ductwork.

[Airchucker]

Duct sensor... Cntrl guy replaced the 2.7 setting with 1.0 sup and .5 ret stpt. No help. No change.

[John Culpepper]

All of the VAVs are working properly? How far down the duct is the senser mounted? My static senser is set at 1.5"

[supertek65]

you have a problem!!

ok for motor and vfd
BAD for VAV's!!!!!!!!!!!!!!!!!!

find out what is wrong with your pressure transducer
or
maybe the drive is in bypass/ hand

is it 0-10 volts
2-10 volts
3-8 volts
4-20 Ma
?????????????????????????????????????????????????? ????????????

better fix it!

[Airchucker]

I thought stpt was too high. 1.5 sounds better. 0-10v. new building 2 floors 1 70 ton per floor... both these units are doing the same thing.

[John Culpepper]

My guess would be that they weren't set up right from the beginning. I would check static pressure toward the end of the duct, and then start shutting down VAVs and see if static will climb then check your 0 - 10 volt signal and see wheather or not it is changing to match the static pressure. It could be the senser isn't in the right place.

[Airchucker]

Guy's this building has just been balanced at the 2.7 stpt. Still working with installers. Cntrllers and TAB. What should I do? Should I accept the balance report?? People are slow to come back inside finished.

[Airchucker]

Cntrl guy says install or design problem. He checked sensors...Just got the alerton computer hooked up...I will check to see if they back off closing vav's.

[flange]

you need to find out what design static is suppposed to be prior to making arbitrary changes. get out the M drawigs, find the schedule and get design numbers. next get a magnehelic and check actual static at the sensor location, and review the sensor location on the drawings, it should be roughly two thirds of the way down your longest duct run. if everything there is right, then you need to look at box setup to be sure your minimums and max settings are right. I would sample a few boxes prior to going nuts on all of them. dont let anyone tell you which ones to check. i just found a job where the minimums were set fifty cfm below the max settings on every box. on one boxfor example, max was four hundred fifty, min was four hundy. had 1.5 kw electric heat. no wonder it couldnt work right.

[Tech Rob]

double yaskawa drives at 100% for weeks now. How long will they last?

I put new tires on my car, how many miles can I drive before my engine blows up?

[Big Unit]

The drives shouldn't be affected by the speed. They are only passing the power on to the motor.

[maxster]

if your doing a discharge air setpoint on temp,and the space is comfortable where is all that air :eek2: going with the vavs going to and from minimum...if your space is at setpoint you should be doing floating 30HZ..what and where is your setting for static? 1.5" max for a commercial space .5" at the boxes to react on the pickup tubes

[chadtech]

Cntrl guy says install or design problem. He checked sensors...Just got the alerton computer hooked up...I will check to see if they back off closing vav's.




So what are the duct static sensors reading? I'm assuming less than the setpoint!! What are the VAV temp settings and air valve positions, as someone has said all that air has got to be going somewhere. The test and balance should have been done with the main static at the design pressure.

[Dowadudda]

he's asking if they stay at 60hz for long time is it gonna hurt em. NO it won't.

why there at 60 all the time is suspicious.

With that we can ask 1000 questions. It might be in hand. who knows what the poster knows. Not very specific.

[davo]

Had this happen to me once.
I found the T&B report said all fine, but the system could never get to the setpoint. always running at 60Hz. Found drive pully open over 50%, and motor drawing @ 55% of FLA @ 60Hz. Closed pullies, and motors slowed way down, good air flow everywhere, and no problem ever since. 6 years ago.

I had another one where the blower was going backwards. T&B blamed faulty ductwork.

We need some good T&B guys down here.

[jslimjeff]

A drive running at 60 HZ is about 2 % less efficent than a 60 HZ starter due to losses in the drive. However drives dont care what the frequency is they are only affected by current. As long as the consumption is below the nameplate all is well.

But as all others suggest.. Check balancing and settings.
The drive is not saving you money. It is costing you money at this point.

For some custom projects we have created a circuit to place the drive into bypass when the speed was at 60HZ for prolong periods... IE High temp days, Economizing.....



Jeff