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SIMILAR PRODUCTS
| SGMGH-03ACB61 |
| SGMGH-03ACB6C |
| SGMGH-05A2A2B |
| SGMGH-05A2A61 |
| SGMGH-05A2ASC61 |
| SGMGH-05ACA61 +SGDM-05ADA |
| SGMGH-05ACA6C |
| SGMGH-05ACC21 |
| SGMGH-09A2A21 |
| SGMGH-09ACA21 |
| SGMGH-09ACA2B |
| SGMGH-09ACA2C |
| SGMGH-09ACA61 |
| SGMGH-09ACA6B |
| SGMGH-09ACA6C |
| SGMGH-09ACB61 |
| SGMGH-09ACB6B |
| SGMGH-09PCA-AM14 |
| SGMGH-12A2B2 |
| SGMGH-12A2B21 |
| SGMGH-13A2A-YR13 |
| SGMGH-13A2A-YR23 |
| SGMGH-13A2A-YR23A |
| SGMGH-13A2A-YR24 |
| SGMGH-13ACA |
| SGMGH-13ACA21 |
| SGMGH-13ACA61 |
| SGMGH-13ACA6C |
| SGMGH-13DCA61 |
| SGMGH-1AACA61 |
| SGMGH-1EACA61 |
| SGMGH-20A2B2C |
| SGMGH-20ABA6C |
| SGMGH-20ACA61 |
| SGMGH-20ACA6B |
| SGMGH-20ACA6C |
| SGMGH-20ACB2C |
| SGMGH-20ACB61 |
| SGMGH-20D2A21 |
Grounding
(a) Motor Frame
Always connect servomotor frame terminal FG to the SERVOPACK ground terminal . Also be sure to ground the ground terminal .
If the servomotor is grounded via the machine, a switching noise current will flow from the SERVOPACK power unit through motor stray capacitance. The above grounding is required to prevent the adverse effects of switching noise.
(b) SynqNet Communication Cable
Make sure to keep the box or power line separate from the SynqNet communication cable because the cable is easily influenced by noise.
If noise is a problem, coil the communication cable two turns around the ferrite cores on the SERVOPACK end and the controller end. Refer to the following diagram.
(c) Noise on the Reference Input Line
If the reference input line receives noise, ground the 0 V line (SG) of the reference input line. If the main circuit wiring for the motor is accommodated in a metal conduit, ground the conduit and its junction box. For all grounding, ground at one point only.
All grounds must be made to only one point in the system.
Manual Motor Starters
A manual motor starter is package consisting of a horsepower rated switch with one set of contacts for each phase and corresponding thermal overload devices to provide motor overload protection.
• The main advantage of a manual motor starter is lower cost than a magnetic motor starter with equivalent motor protection but less motor control capability.
• Manual motor starters are often used for smaller motors - typically fractional horsepower motors but the National Electrical Code allows their use up to 10 Horsepower.
• Since the switch contacts remain closed if power is removed from the circuit without operating the switch, the motor restarts when power is reapplied which can be a safety
concern.
• They do not allow the use of remote control or auxiliary control equipment like a magnetic starter does.
A normal servo, which lags the command, will round the corner as the second axis command builds up and the lag in the first axis dissipates. With feedforward, since the machine is coincident with the command when the corner is reached and the feedforward for the first axis is removed in a step fashion, the first axis will respond similar to its step response.
What About Servo Update Time?
Control vendors update their servos on a regular time basis. Servo update time is the time interval between
the calculations for command (C) minus feedback (F) to give error (E). In other words, it is how often a correction (E) is calculated. Update times vary from microseconds up to 16 ms (milliseconds) for most
controllers. Some vendors initially updated servos once per scan with their programmable controller.
However, variations in scan time caused severe servo problems, especially when axes needed to be
coordinated. Typically the software for closing the servo loop is written in assembly language which is OK
since it is invisible to the user. Assembly language is the best to use because it is the most efficient with
computer time, especially since it interrupts the computer so often. To conserve computer time, it would
seem logical to choose the longest servo update time possible, however, sample data theory would tell one
to choose the shortest. In a study of this conducted by myself and Dr. John Bollinger of the University of
Wisconsin, the conclusion was that a 10 ms servo update time would be more than adequate for heavy duty
industrial machinery. This has proven to be true.
Many vendors are also closing the velocity loop digitally with the computer. Since the velocity loop is
inside the position loop, the velocity bandwidth must be at least five times greater, thereby requiring a
sample time of 2 ms or better.
There are two basic approaches to computer closure of the servo loop. One is to devote a computer to each
axis. The other is to have a central computer that closes all axes. Each vendor will have a list of reasons why his is best, but here are several basic observations.
