new to chillers

[johnnyb]

I have only worked on 3 chillers and not very extensively. I see that there is a lot of experience and well trained techs out here in this forum. I mostly work with small owners (customers) that usually use whomever is available (me) rather than factory support. I am not factory trained and don't know the details of chillers. Any help is appreciated.

I am working on a Worthington 8 cyl. model BOX-0838-0130-0 SN AK-45101 and it says Senty Recip. It has a part winding start. I this the same as a Y/Delta Starter ?
I have leak and am trying to isolate the lines,condenser(air), receiver, barrel, and comp, to locate leaks. The service valves are not all sealing, is there a way to make them seal ?

The receiver appears to be an old water cooled condenser, as it has two 2 1/2" pipes and a 3" pipe at one end which have been cut off. You can see the unused water tubes inside the vessel. It is a model 14xcds4141 . Is it an old condenser ?

[RichardL]

As to your first question as to the part winding start the same a Y-Delta the answer is No. A Part winding start on say a 60hp compressor has 2 identical motors rated @30HP each that are brought on with a brief time delay between the two. It was just one of the many...many ways of achieving the "Incremental Start" requirements that many of the larger cities imposed on motors greater than 20HP. As far as getting the suction-discharge service valves to hold you can try to open and close them "Several" times each in an attempt to clean off the valve seats....Sometimes it works....sometimes it does'nt. When the Worthington plant in Decatur Alabama closed in the 70's I was with the company that bought all the remaining 3V and 4V carcasses and brought several tractor trailer loads back to Atlanta. Unlike the Big Trane "E" models the big 4V had the capability of using an extended stroke crankshaft for lower temp. operation.

[zw17]

Post count 14.

Join date 2007.

Either get your post count up and show your creds to become a pro member or hire a chiller tech.

This isn't a free DIY site.

[Tech Rob]

As to your first question as to the part winding start the same a Y-Delta the answer is No. A Part winding start on say a 60hp compressor has 2 identical motors rated @30HP each that are brought on with a brief time delay between the two. It was just one of the many...many ways of achieving the "Incremental Start" requirements that many of the larger cities imposed on motors greater than 20HP. As far as getting the suction-discharge service valves to hold you can try to open and close them "Several" times each in an attempt to clean off the valve seats....Sometimes it works....sometimes it does'nt. When the Worthington plant in Decatur Alabama closed in the 70's I was with the company that bought all the remaining 3V and 4V carcasses and brought several tractor trailer loads back to Atlanta. Unlike the Big Trane "E" models the big 4V had the capability of using an extended stroke crankshaft for lower temp. operation.

LOL! Richard, I see what you did there!

[R123]

Richard accurately described the part winding start. A Y Delta starter starts the motor in the wye configuration, then after the motor is up to speed, the contactors rewire it to the delta configuration.

As zw17 said, you need to apply for pro status if you want any more info. You only need 1 more post.

[johnnyb]

I don't know if this weill count as another post but, I am an HVAC CONTRACTOR but I just don't have much experience on chillers. Today I got mor nitrogen as I ran out yesterday as the system took all that I had in one tank another 80 cu ft tank full. I have it up to 175 psig now and hopefully will be able to determine which section is leaking tomorrow. AS I was pressurizing the system from the outdoor air cooled condenser , I got som more gurgling at the cchiller and the compressor started filling w oil. It is near the top of the sight glass now. I supose that oil is the amount that stays put in the lines and condenser while the system is running. It has that funny (to me)(as I have never seen another) 3 port solenoid valve connected to the expansion valve, liquid line, and suction line to control the txv. Do you set the super heat with the stem on the bottom of the txv the same as any other txv ? I assume that the solenoid is either on or off. Just a pilot valve to conttol the txv ? How does it work ? must give the equalizer pressure to the txv. ???

Thanks for your help so far and in advance for any more. Ihave wired a y delta many years ago and ithad to be a 9 pr 12 lead motor as I recall to be able to configure it y or delta with the two contactors. Our local power co requires reduced voltage starting on anything over 50 hp.

[secorp]

I don't know if this weill count as another post.

Yes it does. However "mesa thinking" you in very deep water way over your head.

[RichardL]

The little 3-way solenoid valve you refered to connects the TEV equalizer line to the suction line leaving the evaporator during operation. To pump the unit down, using the TEV as a liquid line solenoid valve, the 3-way valve connects the hi-side pressure to the equalizer port on the TEV forcing the TEV to close and pumping the unit down. It saves the cost of a full size liquid line solenoid by doing this. I cannot think of any other make-model that used the TEV to pump the system down..

[supertek65]

that is so frikkn cool

any pics??????????

The little 3-way solenoid valve you refered to connects the TEV equalizer line to the suction line leaving the evaporator during operation. To pump the unit down, using the TEV as a liquid line solenoid valve, the 3-way valve connects the hi-side pressure to the equalizer port on the TEV forcing the TEV to close and pumping the unit down. It saves the cost of a full size liquid line solenoid by doing this. I cannot think of any other make-model that used the TEV to pump the system down..

[Tech Rob]

I don't know if this weill count as another post but, I am an HVAC CONTRACTOR but I just don't have much experience on chillers. Today I got mor nitrogen as I ran out yesterday as the system took all that I had in one tank another 80 cu ft tank full. I have it up to 175 psig now and hopefully will be able to determine which section is leaking tomorrow. AS I was pressurizing the system from the outdoor air cooled condenser , I got som more gurgling at the cchiller and the compressor started filling w oil. It is near the top of the sight glass now. I supose that oil is the amount that stays put in the lines and condenser while the system is running. It has that funny (to me)(as I have never seen another) 3 port solenoid valve connected to the expansion valve, liquid line, and suction line to control the txv. Do you set the super heat with the stem on the bottom of the txv the same as any other txv ? I assume that the solenoid is either on or off. Just a pilot valve to conttol the txv ? How does it work ? must give the equalizer pressure to the txv. ???

Thanks for your help so far and in advance for any more. Ihave wired a y delta many years ago and ithad to be a 9 pr 12 lead motor as I recall to be able to configure it y or delta with the two contactors. Our local power co requires reduced voltage starting on anything over 50 hp.

IMO, in most cases, you shouldn't have to pressurize the thing to 175 psig to find the leak(s). I rarely have to go above 50 psig using nitrogen/trace gas with high-press DX equipment.

Only 6 lead and 12 lead motors are used with wye delta starters. Wye delta is much different than part-winding, which Richard described in an earlier post. Wye delta uses at least 3, and sometimes 4 contactors, depending on if it's open or closed transition. It's not a reduced voltage starter. It's a full voltage, reduced inrush type of starter.

[R123]

Only 6 lead and 12 lead motors are used with wye delta starters. Wye delta is much different than part-winding, which Richard described in an earlier post. Wye delta uses at least 3, and sometimes 4 contactors, depending on if it's open or closed transition. It's not a reduced voltage starter. It's a full voltage, reduced inrush type of starter.

A wye delta starter is a reduced voltage starter. On a 460 volt motor, when it is starting up in the wye configuration, the individual windings see 277 volts. The 460 volt line voltage is being applied across 2 windings so voltage going across 1 winding (measured from 1 incoming leg to shorting contactor) is 277 volts. When the starter transitions to delta, full 460 volts is applied to each individual winding.

[Tech Rob]

And if you measured from T1 to T2 when the motor was running in wye, what would you have? 460 volts, right? In the context of a closed-transition wye delta starter, the shorting contactor is the equivalent of an internal connection on a 9 lead or a 3 lead wye-wound motor.

I have to admit, I have never thought of this from your perspective, and I have never heard it taught that way, either. It's interesting, and what you are saying makes perfect sense, because you are only getting half a phase through each physical winding in wye.

When the motor is running in wye, T1-T4 and T2-T5 are one in the same. The two put in series create one winding of a greater resistance, which reduces inrush current.

[DITAW]

have to agree with 123, in the wye connection the motor will see a lower voltage and lower starting torque allowing the inrush to be lower and take longer to come up to speed, then once it switches to delta the motor will see full voltage.

[Tech Rob]

Well, there's no real argument here, as we're just discussing semantics. I learned something, and I agree with him, too. The wye-delta starter has no means of reducing the voltage at the motor terminals. However, the effect on the motor is the same as reduced voltage because in wye, the motor only sees 58% of the line voltage through each winding.

[R123]

When the windings of a 3-phase motor are connected in WYE:

The voltage applied to each winding is reduced to only (1 /.'/'3) [1 divided by root three] of the voltage applied to the winding when it is connected directly across two incoming power service line phases in DELTA.

The current per winding is reduced to only (1 /.'/'3) [1 divided by root three] of the normal running current taken when it is connected in DELTA.


So, because of the Power Law V [in volts] x I [in amps] = P [in watts],
the total output power when the motor is connected in WYE is:

PS = [VL x (1/.'/'3)] x [ID x (1/.'/'3 )] = PD x (1/3) [one third of the power in DELTA]

Where:
VL is the line-to-line voltage of the incoming 3-phase power service
ID is the line current drawn in DELTA
PS is the total power the motor can produce when running in WYE
PD is the total power it can produce when running in DELTA.

A further disadvantage when the motor is connected in WYE is that the total output torque is only 1/3 of the total torque it can produce when running in DELTA.


Attached is a good presentation of how a Trane closed transition wye delta starter works.

[jayguy]

a wye delta motor is NOT a reduced voltage motor. it recieves the full voltage (that the building can provide) at all times (except in Open Transition starters).

Most (but not all) VF drives are reduced voltage starters.
Depending on how you look at it, a Solid State Starter is reduced voltage starter (but not really).
Primary Resistor is reduced voltage starter.
MultiPoint Reduced Voltage is a reduced voltage starter.
Auto Transformer is a reduced voltage starter.

a wye-delta starter is not a reduced voltage starter. changing the order of the windings does not change the incoming voltage. it does change the resistance and reactance of the motor...but the motor/starter is still full voltage.

[johnnyb]

Her eI found this already on my own computer. Maybe a little more info.

WE cut the suction and liquid lines to the chiller barrel yesterday to pressure test it to see if it is leaking. I suppose if it is we will probably scrap it all. we have drained about 1 1/2 gal. of oil and the compressor is still at the top of the sight glass.WE could not get the service valves to seal even after opening and closing them several times. Thanks to whomever replied with that suggestion any way , even if it didn't work.


This method is actually reduced voltage but is accomplished by changing the motor phase connections such that a winding that is designed to run with phase voltage equal to line voltage on delta connection is wye connected for starting to put less than line voltage on each phase. Effectively, the voltage is reduced by 1.732 factor. The impedance seen by the power system is 3 times the impedance of the delta run connection.

[johnnyb]

To all but mostly to Tech Rob,

wEare pressurizing mostly to see if there are any leaks. I ahve never had much succes with sniffers. I have had about 5 and we have a dtek but we alqays go back to dy e or an ultrasonic. Is there another way other than orssure testing to prove if asystem is leaking or not ? This thing has 100 ft line set of 1 3/8 liquid and 2 1/8" discharge to the air cooled condenser. Any ideas on how much a new evaporator or reciver would cost ? What would I do ; just get anew one from Carrier or similar ?

[johnnyb]

Gee, I should proofread my text and improve my typing skills !

[R123]

a wye delta motor is NOT a reduced voltage motor. it recieves the full voltage (that the building can provide) at all times (except in Open Transition starters).

Most (but not all) VF drives are reduced voltage starters.
Depending on how you look at it, a Solid State Starter is reduced voltage starter (but not really).
Primary Resistor is reduced voltage starter.
MultiPoint Reduced Voltage is a reduced voltage starter.
Auto Transformer is a reduced voltage starter.

a wye-delta starter is not a reduced voltage starter. changing the order of the windings does not change the incoming voltage. it does change the resistance and reactance of the motor...but the motor/starter is still full voltage.

Yes, the motor TERMINALS receive full voltage no matter how it is configured so I guess in that aspect, it's a full voltage starter. But the INDIVIDUAL MOTOR WINDINGS receive reduced voltage when in wye configuration so in that aspect, it's a reduced voltage starter.

If you google 'reduced voltage starter' in almost all hits, wye delta is listed.

Who knows, maybe I'm wrong, but this is an interesting discussion.