Wednesday, December 10, 2014

Leading global manufacturer of electrical and mechanical drives, motion control and automation technology, Lenze Americas recently introduced its innovative Smart Motor designed for applications ranging from material handling to packaging automation. Blending the simplicity of a conventional AC motor with electronic drive control technology, Lenze’s versatile Smart Motor was showcased at PACK EXPO in September.

Offering a highly versatile and powerful package, the Smart Motor delivers maximum standardization-drastically reducing (by up to 70 percent) the number of different motor variations customers might otherwise need. Equipped with control intelligence in the terminal box, the Smart Motor provides design flexibility for speeds from 500 to 2,600 rpm, while maintaining constant torque. The easy-to-install motor enables mains and starter applications to be handled with greater ease than with conventional motors.

The Smart Motor complies with IES2 the top efficiency class for drive systems, while maintaining a small footprint. Among its standard functions, the Smart Motor enables speed switchovers and the ability to set individual start-stop ramps. Integrated ramps ensure smooth acceleration and deceleration to protect the system mechanics and product being handled. The Smart Motor features full motor protection, eco mode for energy savings, and digital outputs for speed selection, direction and status messages.

Leading global manufacturer of electrical and mechanical drives, motion control and automation technology, Lenze Americas has introduced its new g500 gearbox range, developed to transform motor speed into torque as intelligently and accurately as possible. Designed for mechatronic integration with the Lenze Smart Motor, the finely tiered series of g500 gearboxes enable efficiency of over 94 percent across the entire transmission range.

The new g500 gearboxes minimize losses, so the motor can generate less energy, which improves the bottom-line efficiency of the entire system. The lower level of generated heat increases the overall service life. The g500 gearboxes are designed for total integration with the Lenze Smart Motor. A single, efficient motor for many applications, the Smart Motor offers numerous integrated functions for material handling applications, including higher starting torque and freely adjustable speeds between 500 and 2,600 RPM, which reduces the required number of drive versions by up to 70 percent. The compact Smart Motor meets the highest requirements in energy efficiency and can be conveniently operated using an NFC-capable smart phone.

The helical, helical-bevel and shaft-mounted helical g500 gearboxes are now available in sizes of 45 to 600 Nm constructed in aluminum housings. In 2014, Lenze plans to release g500 gearboxes with up to 13,000 Nm ratings produced in cast iron. The g500 gearboxes can be combined with the Lenze Smart Motor, in addition to IE2 MH three-phase AC motors, the inverter-optimized MF motors, and the MCA and MCS servo motors.

All NEMA frame low voltage motors are typically designed with a 1.15 Service Factor (SF). It is common on some higher horsepower, or application-specific motors to be 1.0 SF based on special design, enclosure size etc. There are two aspects to SF:

The first is motor temperature. Temperature rise is described thoroughly in last month’s issue. The relationship between motor heating and current is a square function, and motor current draw is generally proportional to load. Heating is a function of current2 x resistance x time. This is usually referred to as current2 x time, or I2t. At SF loading, if current is 1.15 x rated, the heating effect will be 1.152 = 1.32 x normal. This roughly means that if the temperature rise at full load is 80°C (‘B’ rise) the temperature rise at 1.15 SF loading will be in the order of (1.15)2 x 80°C = 105.8°C (‘F’ rise). This is why most manufacturers design a motor to have a B rise or less at full load for a 1.15 SF motor.

[ASIDE: This clearly shows how a motor designed with a ‘B’ rise @ 1.15 SF, which is 90°C, is better than a motor with a ‘B’ rise @ 1.0 SF, because this motor with a ‘B’ rise @ 1.0 SF, loaded to 1.15 SF will have a temperature rise of 105.8°C.]

In general, Toshiba motors use an insulation system that is Class F (155°C) rated and has B rise or less @ 1.0 SF (80°C), and in the case of the EQP Global® series, all motors 445T frame and smaller have a B rise or less @ 1.15 SF. This means that the insulation will be well below design temperature of the insulation system even when operated at continuous overload up to 115% of nameplate. The smaller the motor frame, the larger the thermal margin, and the greater the overload a motor can handle. This is why you’ll often see motor manufacturers advertise as a 1.25 SF rating on the smaller frames. Furthermore, in the case of TEAO (Totally Enclosed Air Over) motors used in ventilation fans for the mining industry, the increased air flow from being mounted in the center of the fan (3000 ft./min.) often allows for 1.35 SF as standard.

The second issue is mechanical capability. Bearings are an important part of the mechanical capability and life of a motor. For every 15°C hotter that a bearing runs, the grease life is cut in half. Open-style bearings run cooler than sealed or even shielded bearings. When a motor is run into its SF, it runs hotter and consequently, so does the bearings. As a result, grease life, or re-greasing intervals, is reduced.

Shaft strength is another consideration when designing a motor with a SF capability. A 1.15 SF motor has a strong enough shaft to handle the additional continuous shaft load. Although this is not usually an issue with smaller HP motors, it becomes a real consideration on larger machines. Just because a motor is specified with a B rise at full load doesn’t necessarily mean that it is suitable to be rated as a 1.15 SF motor.

The preceding issues are concerned with sinusoidal operation. When an ASD is utilized, the motor sees additional heating over and above the I2t heating effect. This is due to the harmonic content of the drive’s output waveform. This additional heating can range from 5% extra heating for a good quality PWM drive with an adequately high carrier frequency to up to 30% additional heating for a square wave variable voltage inverter (VVI) drive. When using an ASD on a 1.15 SF motor, as a rule of thumb, you should now treat your motor as being a 1.0 SF motor, as a result of the heating from the ASD.

A 1.15 SF motor installed “across the line” can be operated at 1.15 SF. However, you will theoretically get a varying insulation life depending on the operational temperature of a motor on a specific application. For a fixed set of conditions on an application, the motor manufacturer with the largest thermal margin (difference between actual design temperature rise v. insulation class) will give you a longer insulation life span overall.

Leading global manufacturer of electrical and mechanical drives, motion control and automation technology, Lenze Americas has unveiled its g700 series of purebred planetary gearboxes designed for servo applications with demanding requirements relative to overload capacity and dynamics. The new gearbox series extends the company’s range of solutions for servo motor applications.

The g700 can be used in conjunction with Lenze’s synchronous and asynchronous servo motors, as well as a single gearbox with a servo motor. Designed specifically for servo application, the one-, two- and three-stage planetary gearboxes are available in five sizes and cover torques ranging from 177 in-lbs to 7080 in-lbs.

The special handling of the toothing edge, which includes grinding and honing, and the precise, balanced clamping system for the motor, help to minimize the noise generation. As a result, a noise of ≤58 dB(A) is achievable which corresponds to a quiet conversation.

The g700 is a gearbox with lowest life-cycle costs. The gearbox is robust and reliable and achieves a service life of 30,000h. It does not need lubricant change or top up and is completely maintenance-free.

“Our growing solutions portfolio is scalable and precisely tailored to the requirements of servo applications,” said Robert Gradischnig, electro-mechanical business development manager, Lenze.

“This new g700 planetary gearbox is another step forward in our ‘easy engineering’ philosophy. Whether they need products for relatively simple machine tasks or highly complex ones, our customers can easily find the right solution for their application.”