Appendix A

Load Weighing / Torque Feed Forward

In many advanced elevator applications, the system is designed to weigh the elevator load to offset the counterweight of the car. We also refer to this as a torque feed forward application. Both the Baldor AC Vector (Series 18H and 22H) and Series 20H SCR Controls can be programmed to use the torque feed forward option (Level 1 Input block; Command Select parameter, 10V w/Torq FF).

In a typical installation, a car is balanced with a 40% load. In order to move the car in the up direction, the drive should receive a forward speed command. If the car is full, then it would have to generate positive torque in order to move the car forward or in the up direction.

A load cell is installed on the car to measure the loading of the car. Typically, 10 volts output from the load cell equals a full car and 0 volts equals an empty car. This means that 10 volts equals a value of positive torque and 0 volts equals a smaller absolute value of negative torque.

Since the output of the control requires the torque feed forward signal to be bipolar, then the load cell voltage needs to be scaled properly in order to generate the appropriate values of torque. A customer supplied signal processor board can be used for this purpose (the load cell could have this feature built in).

In a typical elevator application, the accelerating torque is significantly greater than the holding torque (or torque required at zero speed), which means that it is not necessary to use the full range (±10 volt) capability of the torque feed forward. This is shown in Figure A-1. A ±5 volt output of the signal processor board is probably adequate for most typical elevator applications.

Figure A-1 Typical Elevator Application

0-10V

 

±5V

JOG LOCAL PROG

 

FWD DISP

Signal

 

Signal

STOP RESET

 

 

 

REV SHIFT ENTER

 

Signal

 

 

 

Processor Board

 

 

Load

Cell

Baldor Series H

Vector or

DC SCR Control

Elevator Car

Counterweight

MN770

Appendix A-1

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Baldor MN770 manual Appendix a, Load Weighing / Torque Feed Forward
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MN770 specifications

The Baldor MN770 is an impressive industrial motor designed for a variety of applications, showcasing robust construction and advanced technology. Known for its reliability and efficiency, the MN770 is manufactured by Baldor Electric Company, a prominent name in the electric motor industry.

One of the main features of the MN770 is its high-efficiency design. This motor adheres to stringent efficiency standards, helping to reduce energy consumption and lower operational costs. It typically meets or exceeds NEMA Premium Efficiency ratings, making it an excellent choice for businesses looking to optimize their energy use.

The MN770 motor is built with a durable cast iron frame, ensuring longevity and resistance to harsh operating conditions. Its weatherproof design is ideal for both indoor and outdoor applications, making it suitable for various environments, including manufacturing plants, water treatment facilities, and agricultural operations.

Another significant characteristic of the MN770 is its versatility. The motor is available in a range of horsepower ratings, allowing users to select the model that best fits their specific needs. Additionally, it offers various mounting configurations and voltage options, further enhancing its adaptability for diverse applications.

The motor utilizes advanced insulation systems and cooling technologies to ensure optimal performance and a longer lifespan. The robust design helps to dissipate heat effectively, enabling the motor to operate efficiently even under heavy loads. This characteristic is essential for applications requiring continuous operation without compromising reliability.

Moreover, the Baldor MN770 incorporates advanced design features such as precision-balanced rotors and high-performance bearings. These characteristics contribute to reduced vibration and noise levels, promoting a quieter working environment and improving overall operation efficiency.

In summary, the Baldor MN770 motor stands out due to its high efficiency, robust construction, versatility, and advanced technologies. Its ability to perform reliably in various industrial applications makes it a popular choice among engineers and facility managers. Investing in the MN770 not only enhances operational efficiency but also supports sustainability efforts by reducing energy consumption in industrial environments.
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