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Electrical machine software

You can categorize the electrical machine software into 2 basic types:

1) FEA packages that may or may not have a front end for analyzing motors. These are available from companies like Vector Field (now Cobham), Infolytica and a few others.
2) Motor design specific software such as the SPEED software, RMxprt and MotorSolve from Infolytica.

In the first category, the FEA packages are expensive because they are general purpose modeling packages. The motor add-on is usually limited mostly to the building the model and perhaps some specialized post-processing for motors. Their main advantages are:

1) 2D and 3D versions.
2) The user is free to define what analysis he wants to perform since they have very advanced general post-processors.

Their main disadvantages are:
1) Cost, they can get very expensive depending on the options you require.In some cases, the motor design module is a cost option.
2) Although they have general post-processors, many users require a lot of training in order to be able to get useful information.
3) Geometry input can be a lot more complicated since the front-ends typically have a limited number of geometries available.

The second category, the motor design software, is specifically designed for motor analysis. It can be magnetic circuit based such as SPEED and RMXprt or full finite element based such as MotorSolve. The magnetic circuit type of software has been available for a long time but it has only been recently that full FEA based motor design packages have become available.

The general advantages of software of this type are:

1) Template based input so the user simply chooses the motor geometry, stator and rotor and sets the parameters for the geometry. The input is therefore very simple but limited to the templates that are implemented in the package.
2) Post-processing is specialized and presented in a form that a motor designer can use it.

The general disadvantages of this type of software is:

1) No specialized post-processing is available directly from these packages unless added by the software provider in a new release.
2) Geometries are limited to the templates and adding templates may be very difficult and has to be done by the software provider.

What factors cause Current unbalance

1. Voltage unbalance in supply side (1% volts could easily be 10% current).
2. Physical differences between individual stator coil shapes and connections causing small (but noticeable) resistance changes.
3. Unsymmetrical magnetic circuit – not as big a deal in the smaller “ring” lamination designs, unless highly saturated.
4. Lightly loaded machines will exhibit far higher unbalance than those loaded closer to the full nameplate rating (mostly due to the magnetizing current requirements and associated core/stray loss).

For quick solution measure the current in the three phases, then change the three supply terminals by shift the three terminal to rotate the motor in the same direction, and measure again the current, if the high current move with a certain phase (example: phase L1 of supply read high current in the two case above) the problem is from supply, you can then measure the voltage at motor terminal to be sure that the control circuit and cable are good.

Energy Efficient Motor VS Standard motor

This is a very simplified comparison for a very complex issue. Every motor manufacturer is somewhat different in their approach, and there are literally thousands of design details in each machine that can be accommodated as the designer balances efficiency VS performance VS cost VS reliability VS safety VS manufacturability.

To generalize a bit, take a look at the following list. Not everything is there (not by a long shot!) but there should be enough to give you a reasonable overview. Note that some items are “design” related, while others are “operation” related.

1. Use a lower loss material for both stator and rotor laminations.
2. Use a larger copper cross-section for the same power rating.
3. Skew rotor winding with respect to stator winding.
4. Use more magnetic material (diameter, length, or both) to reduce flux densities.
5. Effectively size the machine for a somewhat higher rating than nameplate (because the typical peak of the efficiency curve occurs somewhere between 70 and 85 percent “rated” load).
6. Operate the machine at reduced temperatures and/or increase coolant flow.
7. Limit input frequency and/or voltage variation to tighter tolerance (note that this is a specification approach, not a manufacturing approach).
8. Better bearings / lubrication to reduce friction loss.
9. More care taken with internal geometry – i.e. closed slots, large air gaps, generous tooth dimensions, smooth surfaces, etc – to reduce windage.

How to learn PLC technology languages

The PLC languages themselves are fairly similar between different manufacturers. You basically have ladder logic (which looks like a relay contact map), function blocks (which are more akin to an electronic circuit overview) and structured language (of which there are several variants. Most look a lot like high-level programming languages). You might encounter some functions having different names or in-/outputs between manufacturers but most of them look much the same. They have the same functionality although complex programming is easier in structured code. If you have worked with high-level programming, you might want to take a look at structured languages first as these will likely feel familiar.

As for ease-of-use, I usually recommend the larger manufacturers; not because these have the best, cheapest or easiest software but because they have very substantial and comprehensive online support which, for a beginner, is more helpful than a cheap program. The big companies such as Siemens, Schneider, ABB and Rockwell all have very comprehensive online help, programming examples and guides as well as manuals available. Most also have “starter-kits” of their software and hardware available although these of course require some form of budget.

Soft starter MCC control cabinet

MCC is shorted for Motor Control Center. Soft starter MCC control cabinet consists of the following components: (1) input circuit breaker, (2) Soft starter (including electronic control circuit and three phase thyristor), (3) soft starter bypass contactor, (4) secondary-side control circuit (for manual start, remote start, soft start and direct start functions selection and operation), and voltage, current display, fault, running and working status indicators.

We can achieve various complex functions with combinations of soft starter MCC control cabinet. For example: add logic controller to two control cabinets to form a “alternative solution” for building’s fire protection system, sprinkler pumps etc. Couple with PLC (programmable logic controller), we can achieve automatic detection (eg half a month) and shutdown of the fire pump system; couple with corresponding logic controller to make the pump running at low speed and low pressure in setting time when we maintenance the whole system working status. Combine logic controller with several motors for residential pump system and other dedicated systems, active each motor according to actual requirements and also can reduce motor gradually to achieve optimum operation efficiency. Also can achieve multiple motors running by turns according to customer requirements, to make all motors operating life in the same.

Soft starter protection features

1) Overload protection: the soft starter has current control loop to track and detect of the changes of the electric motor current. Achieve overload protection by increasing overload current settings and inverse time control mode, to cut down the thyristor and send alarm signals when motor is overload.
2) Phase loss protection: soft starter detects changes in the three-phase line current all the time, to make phase loss protection response once the current off.
3) Overheating protection: the soft starter detects the thyristors internal radiator’s temperature by its thermal relay, automatic cut down and send alarm signal once the radiator’s temperature exceeds the allowable value.
4) Other features: achieve lots of mixed protection functions by combination of the electronic circuits.

What is the soft stop of an electric motor?

In electric motor stop, the traditional control ways are accomplished by momentary power cutting off. But in lots of applications, it’s not allowed the motor instant shutdown. For example: high-rise buildings, building’s water pump system, it will appear huge water hammer during instant shutdown, to damage the pipe, even the pumps. To reduce and avoid “water hammer” phenomenon, the pumps motor need be shut down gradually, that is soft stop. The soft starter can meet such requirements. In pumping station, soft stop technology can avoid the pump door damaged of the pumping station, to reduce maintenance costs and maintenance works. The soft stop function in soft starter is, when the thyristor gets stop instruction, decrease conduction angle gradually from full conduction, and achieve full closed after a certain time. Stopping time can be adjusted according to actual requirements within 0 – 120s.

Soft starter energy saving principle

Induction motor is inductive load, the current lags the voltage, most electrical appliances are the same. In order to improve the power factor we need to use capacitive load for compensation, parallel capacitors or with synchronous motor for compensation. Reduce motor excitation current also can improve the power factor (HPS2 saving function, reduce excitation current by reducing voltage at light loads, to increase COS∮). Energy-saving operation mode: decrease voltage in light loads to reduce excitation current, the motor current divides into the active component and reactive component (excitation component), to increased COS∮.

Energy saving operation mode: when the motor load is light, the soft starter working at energy-saving conditions, PF switch to Y position, under the current feedback action, the soft starter reduces the motor voltage automatically, to reduce excitation component of the motor current. Thereby improving the power factor of the motor (COS∮). If the contactor in bypass state, this feature cannot works. TPF switch provides energy saving features with two reaction times: normal speed and slow speed. The soft starter operation in energy saving state automatic (In normal and slow speed), saving 40% energy in no-load and 5% with load.

How is Vector Control improving motor output torque capability?

1: Torque boost: this function is the variable speed drive increases output voltage (mainly in low frequency) to compensate the torque loss due to voltage drop in the stator resistance, thereby improving the motor output torque.

2: Improve the motor insufficient output torque in low speed
“Vector control” can make the motor output torque at low speeds, such as (without speed sensor) 1Hz (for 4-pole motor, the speed is about 30r/min), same as the torque output at 50Hz power supply (maximum is approx 150% of rated torque).

For the V/F control variable speed drive, the motor voltage increases relatively as the motor speed decreases, which will result in lack of excitation, and make the motor can not get sufficient rotational force. To compensate this deficiency, the variable speed drive needs to raise voltage to compensate for the voltage drop in motor speed decreases. This feature called “torque boost”.

Torque boost function is to improve the variable speed drive output voltage. However, even if the drive increases voltage, the motor torque and current does not increase corresponding. Because the motor includes the torque and other components (such as the excitation) which generated by the motor.

“Vector Control” allocates the motor current value to determine the motor torque current component and other current component (such as the excitation component) values.

Change 230V to 460V for operating an Electric Motor

I have a generator of 3 hp, and it outputs 230 V, and I have a submersible Electric Pump, the motor of which is rated to operate at 460 V, Can I use a step up transformer to increase the voltage output from my generator and power the pump? What more parameters do I need to know of in this case?

Check to see if the generator has 3 phase power output. A typical home generator will provide 230 volt single phase output. You will not be able to step up to 460 volt and start a 3 phase motor with single phase. The only way at that point to generate 3 phase would be to use a VFD with single phase input capability and use the drive to generate 3 phase. You will still need to use a transformer. Variable frequency drives won’t normally behave well on generator power but may for an intermittent load like a submersible pump.