Part winding starters

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Generally 2 methods

1 winding motor
Start with a reduced voltage then transition to rated voltage
autotransformer
resistors intitial in the ckt then bypassed
Wye-delta transfer using contactors, arrange windings wye to start and transition to delta to run

2 winding motors or part winding
1st is a higher impedance low speed to limit inrush
once moving transfer to running speed windings or operate in parallei


good primer
http://static.schneider-electric.us/docs/Motor Control/8600PD9201.pdf


Mostly obsolete due to solid state starters
 
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rlundsrud said:
To do a wye-delta start, you would need a 12 lead motor. I know that isn't exactly what the OP asked, but it is something worth knowing on this topic.
Click to expand...

In the link I posted it shows 3 coil/6 leads???

to start apply V PH/sqrt3 or ph-neut
then transition to delta for full V ph
starting V is 58%
running 100%
 
Ingenieur said:
In the link I posted it shows 3 coil/6 leads???

to start apply V PH/sqrt3 or ph-neut
then transition to delta for full V ph
starting V is 58%
running 100%
Click to expand...
The key is the motor must be rated for applied voltage when connected in the delta configuration, but that is somewhat typical with North American made motors if there is six leads. I believe European motors may be more common to have a six lead motor intended to be used as a dual voltage motor connected wye for high voltage and delta for low voltage.
 
As a water/electric utility, we use part winding start motors for all of our pumps 75HP (probably 100 or so) and below. Some older motors up to 250HP are still part winding start. 25HP and smaller are across the line. All are 480V. They are simple and reliable. Wired just like the link shows. Ours are 6 or 9 wire. They are NOT Wye/Delta. On larger motors, we find that a soft start is less maintenance and allow us to use single voltage, 3 wire motors, which are cheaper. Time delay between start and run is 1-2 seconds. The part winding start reduces inrush current when starting. That makes voltage sags less noticeable on the lines feeding nearby customers. We get enough complaints as it is.....

Here's a link: http://www.usmotors.com/TechDocs/ProFacts/Typical-3ph-Connections/PWS-WYE-Dual.aspx
 
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meternerd said:
As a water/electric utility, we use part winding start motors for all of our pumps 75HP (probably 100 or so) and below. Some older motors up to 250HP are still part winding start. 25HP and smaller are across the line. All are 480V. They are simple and reliable. Wired just like the link shows. Ours are 6 or 9 wire. They are NOT Wye/Delta. On larger motors, we find that a soft start is less maintenance and allow us to use single voltage, 3 wire motors, which are cheaper. Time delay between start and run is 1-2 seconds. The part winding start reduces inrush current when starting. That makes voltage sags less noticeable on the lines feeding nearby customers. We get enough complaints as it is.....

Here's a link: http://www.usmotors.com/TechDocs/ProFacts/Typical-3ph-Connections/PWS-WYE-Dual.aspx
Click to expand...

Here's another link probably more like what we use: http://www.usmotors.com/TechDocs/ProFacts/Typical-3ph-Connections/PWS-WYE-Single
 
PW vs Dual Voltage.

In order to use a motor in a Part Winding start, you must have the windings configured for that, and be able to bring 6 leads to the motor. That's also what you must do for a Wye-Delta start, which is why they are often confused, bu5t they are different. In a PW starter arrangement, the Code requires that each set of winding have separate OL's and possibly separate OCPDs, you have to read article 430.4 very carefully and apply it to your exact situation to understand if the exception applies. Unfortunately, many of the PW wiring diagrams from motor mfrs and some starter diagrams leave that part out because it's not actually their concern. So be careful using ONLY that diagram.

A dual voltage motor is different, although similar. Here in North America, dual voltage will mean there are two sets of windings as well, and you connect them differently for the different voltages, but you only bring 3 leads out to the motor, one set of OLs and one SCPD based on the current at the voltage that you use. The voltages will be 230 or 460V, a 2:1 ratio.

In other parts of the world, "dual voltage" is different because for them; the (nominal) low voltage is 230V and the high voltage is 400V, so the difference is the sq. rt. of 3. Therefore if you connect the motor is Delta, it runs on 230V and if you connect it in Wye (Star) it runs on 400V. That doesn't work for us.

Many motor mfrs sell motors where ALL of the motor coil leads are brought into the connection box, so you as the user can decide in the field what type of starting method and / or voltage you want to use. You can use Wye-Delta, PW, or Full Voltage starting, then you can use it at Low or High voltages. You can ALSO reconnect the same 12 lead motors for dual voltage in IEC world, but you cannot do PW starting for that, which is why they don't have that option.
 
I don't see stuff like this often anymore
usually in older water/wastewater plants

recently saw a 2 speed 6 lead 125 HP 480 vac
used a vfd on the hi-speed configuration
controlled air Q and P with a piping bypass/control valve
 
ActionDave said:
The first link you gave is a star/delta starter. The second link says star only for 480V but you need a special winding. Does that mean you are only using half the windings on start up?
Click to expand...

Yes...you only use half of the winding on startup, then the other half is cut in. That's why they're called "part-winding" start. No special motor that I'm aware of, but then, I wasn't the one doing the ordering, so I can't say for sure. Looking at the diagram, it looks like a standard 9 wire dual voltage motor. Wired with 3 wires from each contactor. We color code ours with tape...one set with one B,O,Y tape and one with two. If I remember right, (been a couple of years), each starter has overloads and the contacts are wired in series, so that if either one trips, the start circuit is opened.
 
Ingenieur said:
I don't see stuff like this often anymore
usually in older water/wastewater plants

recently saw a 2 speed 6 lead 125 HP 480 vac
used a vfd on the hi-speed configuration
controlled air Q and P with a piping bypass/control valve
Click to expand...

The ones we used are not two speed...just part winding. VFD's are not practical for turbine type pumps because that type of pump operates at peak efficiency at full speed. Any lower and flow drops off drastically. Pumps start against a closed valve. The motor reaches full speed almost immediately and then the valve slowly opens hydraulically to reduce water hammer. I know...TMI Just an aside...BIG pumps like in the nuclear days start across the line (with BIG breakers). 13,800V 9000HP. Pretty specialized pumps, though and I doubt you could even build a soft start or VFD for those. Sure are noisy! I know....way off topic, but still kinda cool.:happysad:
 
meternerd said:
Yes...you only use half of the winding on startup, then the other half is cut in. That's why they're called "part-winding" start. No special motor that I'm aware of, but then, I wasn't the one doing the ordering, so I can't say for sure. Looking at the diagram, it looks like a standard 9 wire dual voltage motor. Wired with 3 wires from each contactor. We color code ours with tape...one set with one B,O,Y tape and one with two. If I remember right, (been a couple of years), each starter has overloads and the contacts are wired in series, so that if either one trips, the start circuit is opened.
Click to expand...
Has to be special enough to have two sets of windings and the leads to them made accessible, A motor with only three leads is not going to work with this starting method, and dual voltage 9 lead wye motors wouldn't be able to do it when connected to the higher input voltage;)

Dual voltage delta motors would really need to go with wye-delta method if connected to the higher input voltage.
 
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