Difference between Star-Delta and Reactor Starting Method 1

[Arshad Ahamed]

Greetings,

Recently, I came across a submersible sump pump with Reactor Starting Method, as opposed to Star-Delta or DOL which is mostly what we are experienced in. I've tried researching online but have found the information/explanations to be too complex.

Would appreciate your help in listing the differences between Reactor and Star-Delta starter, with respect to the below points
1. Operation
2. Control panel design and wiring
3. Any specific/special point to be remembered working on this new system.

Regards,
Arshad.

Be curious, and furious in your pursuit for answers

 

[waross]

Reactor starting may have less starting torque than star/delta. It depends.
Reduced starting torque is often acceptable for centrifugal pumps. It depends.
Star/delta starting is subject to severe current and torque transients when the transition to full voltage is made.
Reactor starting, less so.

Bill
--------------------
"Why not the best?"
Jimmy Carter

 

[crshears]

Is it not also the case that wye / delta starting requires a type of motor that has all leads brought out, whereas reactor starting does not? I seem to recall seeing that in numerous diagrams over the years.

CR

"As iron sharpens iron, so one person sharpens another." [Proverbs 27:17, NIV]

 

[waross]

You are correct crshears.
Also, while European six lead motors adapt well to star delta starting, North American motors are typically nine lead motors. A six lead or a twelve lead motor is required for star/delta starting. The nine lead motors have a buried connection(s) that thwart star delta starting.
A star type of nine lead motor has one buried connection.
A delta type of nine lead motor has three buried connections.
Also, while a nine lead motor may be connected internally as either star or delta, the majority are internally connected star.
This prevents the efficient use of the delta connection at standard voltages.

Bill
--------------------
"Why not the best?"
Jimmy Carter

 

[che12345]

Dear Mr. Arshad Ahamed (Mechanical)

Q. " Recently, I came across a submersible sump pump with Reactor Starting Method, as opposed to ..."
A 1. The term " Reactor Starting Method " is by [insertion of reactor in series] in the three lines during starting and [gradually shorted out] in one step or in numeral steps, after completion of the starting process. The (starting torque) is dependent on the [impedance of the reactor tapping].
There are other alternative methods, which is by the use of an (auto-transformer) or (resistors). These methods are widely used in the States, where it is a common practice witch a three-phase motor with only [three wires] hanging in the terminal box. In this case, it is NOT possible to wire it into "star/delta starting " , which required the (start and the end of the three windings), total [six wires] to be brought out and terminated on the connection terminals in the terminal box. This is the standard practice in Europe and IEC world, but NOT in the States.
A2. The " Reactor Starting Method " can achieve higher /lower than " star/delta" starting torque depending on the impedance chosen. In practical application, it is (about equivalent to) a " star/delta" starting. However, it is more expansive, take up bigger room and weight due to the addition (reactor), which is a big chunk of metal with winding on it.
A3. It must be pointed out that if your motor is with only (three wires brought out), this would be one of the methods or the alternative " auto-transformer starting" ... etc. Attention, it would be NOT possible to wired it into " star/delta" starting, as pointed out above.
A4. Motors of the same rating {with six terminal brought onto the terminals] are also widely available in the States. In this case, it is possible to wire it into " star/delta" starting. The starter would be lower in cost, size and weight. However, the starting torque is NOT adjustable. BTW: Even with " Reactor Starting Method " it is usually chosen to start at about the same as the " star/delta" starting torque.
Che Kuan Yau (Singapore)

 

[waross]

A4. Motors of the same rating {with six terminal brought onto the terminals] are also widely available in the States. ?????????????
You may find them in the catalogue but you won't find them on the shelf.
In IEC land utilization voltages tend to be in the ratio of root three to one. Hence 220/380 Volts, 230/400 Volts.
Thus dual voltage motors will be six lead motors suitable for star or delta connection.
In NEMA land the utilization voltages are in the ratio of two to one. 120/240 Volts, 240/480 Volts.
Thus dual voltage motors are nine lead motors suitable for series or parallel connection.
Series parallel starting has been out of favour for quite a while in NEMA land.

Bill
--------------------
"Why not the best?"
Jimmy Carter

 

[jraef]

As mentioned, some people prefer reactor starters over star-delta simply because it is a much simpler starting scheme and any replacement motor can be anything with the right voltage rating, no special configurations and no special skill set in knowing how to connect it. In remote areas where down time can be costly, that can be very beneficial. The drawbacks are generally slightly higher size and cost which, for some, are less important than Mean Time To Repair.


" We are all here on earth to help others; what on earth the others are here for I don't know." -- W. H. Auden

 

[che12345]

Dear All,
1. Say whatever you like, my observation is different practices in different parts of the world.
2. The [root cause] is, in the States the motors are commonly with (3, [NOT 6], 9,12 loose flexible leads) brought out for external connection. With [3 terminals], it is NOT possible to wire it up into [Star/delta starting]. With 6,9 12 terminals etc, connections are more complicated. Therefore Star/delta starting is NOT common.
3. I wish to point out that a (Star/delta starter) is having the [bare minimum]; with three contactors, a timer and an overload. Any other forms i.e. resistor,reactor,or auto-transformer stater has additional items i.e. resistor, reactor or auto-transformer. This additional item adds about 40% to the cost, 50% to the footprint and 100% to the weight. While the (size/rating and number of contactors) used are [about the same}, depending on the design.
4. A Star/delta starter has [six wires to the motor]. This connection is done only [once at the first installation]. No further changes or adjustment is needed for the rest of the service life say 25-30 years. A resistor, reactor or auto-transformer starter has this [additional costly item] which may last for say 15 years due to (insulation deterioration, bad contact resistance or loose connection etc)...
5. My conclusion why Star/delta starting is NOT common in the States is they do NOT bring out all the six terminals, which is the standard practice in Europe and in the IEC land.
Che Kuan Yau (Singapore)

 

[waross]

In IEC land utilization voltages tend to be in the ratio of root three to one. Hence 220/380 Volts, 230/400 Volts.
Thus dual voltage motors will be six lead motors suitable for star or delta connection.
In NEMA land the utilization voltages are in the ratio of two to one. 120/240 Volts, 240/480 Volts.
Thus dual voltage motors are nine lead motors suitable for series or parallel connection. 120/240 Volts, 240/480 Volts.
Actually motors are available on special order in NEMA land with 12 leads.
Further, in NEMA land, dual voltage motors are available with either star or delta internal connections.
Thus a dual voltage motor in NEMA land may be used with star/delta starting on either of the dual voltages.
An IEC motor with star delta starting is only usable on the lower of the dual voltages.

Bill
--------------------
"Why not the best?"
Jimmy Carter

 

[che12345]

Dear Mr.Arshad Ahamed (Mechanical)

Q. " ...submersible sump pump with Reactor Starting Method, as opposed to Star-Delta or DOL which is ... I found the information/explanations to be too complex..... your help in listing the differences between Reactor and Star-Delta starter, with respect to the below points
1. Operation
2. Control panel design and wiring
3. Any specific/special point to be remembered working on this new system. "
A. As you are "mechanical" in profession, my suggestions would be on "electrical" only.
1. Operation: to the operator, it is the same. Normal start stop as usual.
2 Control panel design and wiring. This will be taken care of by the electrical panel builder. Attention: a) inspect the cooling ventilation inlets and outlets, remove any blockage regularly,
b) inspect the reactor [every six months] to ensure there is [no sign of over-heating or crack/deterioration] of the insulation.
3. Any specific/special point to .... The electrical panel builder should be (officially informed) of the [application] and the [estimated number of starts and stops per hour/min]. The pump characteristic and the motor type/rating should be carefully evaluated, to ensure that the starting torque/starting duration is adequate for the application, a join responsibility of the mechanical and the electrical professionals.
Attention: a) the reactor could be [over-heated] if start stop too frequently, which is to be avoided. Do NOT exceed the frequency the electrical panel builder designed for,
b) stop the pump, if it is NOT picking-up speed due to what ever reasons,
c) consult the electrical panel builder for the [appropriate] (thermal overload current setting),
d) seek the advice/work together with the electrical panel builder to adjust for the [optimum change-over time].
Good luck
Che Kuan Yau (Singapore)

 

[GroovyGuy]

Howdy Arshad,
Have you considered RVSS (reduced-voltage solid-state) type of starter, as opposed to reactor or wye-delta type of starter. RVSS starters are very common these days for variable-torque type of loads (such as a centrifugal pump).
I am sure that that the installed cost of a RVSS starter is very similar to the cost of a reactor or star-delta type of starter as well.
GG



"I have not failed. I've just found 10,000 ways that won't work." Thomas Alva Edison (1847-1931)

 

[waross]

Hello Arshad.
As i understand it, you are not designing this but while you work with and are familiar with star/Delta starters, a reactor start pump has been added to your work load and you desire to know what to expect relative to the familiar Star/Delta starters.
Do I understand correctly?

Bill
--------------------
"Why not the best?"
Jimmy Carter