This article, written by Huang Feng of the Wuhan Mitsubishi Industrial Control Technology Center, describes the checks and settings that should be performed before powering on a Mitsubishi CNC machine to avoid burn-out accidents. A practical "Check and Set-up Form" has been designed. For machine tool manufacturers using the Mitsubishi NC system for the first time, their engineers are still hesitant to power on the system after completing the installation and connection, fearing that improper connection might burn out the controller and other circuit boards. Based on debugging experience, the author has designed a "Mitsubishi CNC Power-On Check and Set-up Form," which can serve as a process specification for machine tool manufacturers. The following explains the key issues that should be checked and set before powering on: 1. Power Supply Mitsubishi CNC machines use four types of power supplies: 1.1 Three-phase AC220V The main circuit of the Mitsubishi servo drive uses a three-phase AC220V power supply. Therefore, a power transformer is provided in the electrical cabinet to convert the three-phase AC380V to three-phase AC220V. Before powering on, the servo drive power supply should be disconnected, and its voltage should be measured with a multimeter to confirm that the voltage is three-phase AC220V before reconnecting it. [IMG=Figure 1 System Grounding Requirements]/uploadpic/THESIS/2007/11/20071114161149926193.jpg[/IMG] Figure 1 System Grounding Requirements 1.2 Single-phase AC220V (1) The control power supply of the Mitsubishi servo drive uses single-phase AC220V. Moreover, this power supply is led out from the front end of the main contactor. That is, it is not controlled by the main contactor. The main contactor only cuts off the main circuit power supply of the servo drive and does not cut off the control power supply. The control power supply is cut off by the main circuit breaker. (2) The cooling fan of the spindle motor also uses single-phase AC220V power supply. (3) When the brake unit has a fan, its fan also uses single-phase AC220V power supply. 1.3 Single-phase AC110V When the E60 system uses a CRT display, it uses single-phase AC110V power supply. However, CRT displays are no longer commonly used now. 1.4 DC24V Mitsubishi CNC controllers, displays, basic I/O, remote I/O, Z-axis brakes, and operation panels all use DC24V power. Because commercially available power supplies are generally unstable, Mitsubishi now equips its systems with PD25 power supplies. Before powering on, the DC24V power plugs of the controller, display, basic I/O, remote I/O, Z-axis brake, and operation panel must be disconnected. Use a multimeter to measure the voltage and confirm that it is DC24V +/- 5% before reconnecting. If the voltage is too high, it will burn out the controller and other units. There have been instances where excessive voltage has burned out the controller, display, basic I/O, and remote I/O, so special care must be taken. The Z-axis brake uses DC24V and does not require polarity. The operation panel should also be connected to DC24V; otherwise, the input signals may be invalid. When using a PD25 power supply, the 0V and FG terminals of its DCOUT connector should be shorted. [IMG=Figure 2 Shorting Piece on SVJ2 Type Driver]/uploadpic/THESIS/2007/11/2007111416120790927O.jpg[/IMG] Figure 2 Shorting Piece on SVJ2 Type Driver 2 Grounding Check The importance of grounding in NC systems has been discussed in monographs. Each device must have a dedicated grounding device. Drive in a 1-1.5 meter metal rod separately. Mitsubishi CNC systems must use a single-point grounding method. The controller, display, basic I/O board, remote I/O module, servo driver, and power module of Mitsubishi CNC all have grounding points (grounding screws). These grounding points must be directly connected to the grounding plate of the machine tool system, and then the machine tool grounding plate is connected to the earth. As shown in Figure 1. 3 Termination Resistor R-TM Basic I/O and remote I/O are equipped with termination resistors R-TM. If the system only uses basic I/O, insert the termination resistor R-TM into the RI/O socket of the basic I/O. If the system uses remote I/O, insert a terminating resistor R-TM into the RI/O socket of the remote I/O. [IMG=Figure 3 Source and Sink Connections of Output Signals]/uploadpic/THESIS/2007/11/2007111416121997909E.jpg[/IMG] Figure 3 Source and Sink Connections of Output Signals [IMG=Table 1 Input/Output Models and Connections]/uploadpic/THESIS/2007/11/2007111416123122147C.jpg[/IMG] Table 1 Input/Output Models and Connections [IMG=Table 2 Axis Number Settings]/uploadpic/THESIS/2007/11/2007111416124554524I.jpg[/IMG] Table 2 Axis Number Settings 4. Terminal Plug A-TM The terminal plug A-TM is connected to the last axis of the drive section. If the system only has servo axes, it is connected to the last servo axis. If the system has a servo spindle, connect it to the servo spindle. 5. Shorting Piece As shown in Figure 2, for the SVJ2 type driver, because it has a built-in braking resistor, a shorting piece is connected to the PD terminal before leaving the factory. If an external braking resistor or braking unit is connected to this driver, the shorting piece must be removed. Otherwise, it may burn out the device. The C1-V type driver does not have a shorting piece because it uses a power-type regeneration unit. The R type driver does not have a shorting piece connected at the factory. The R type driver also uses a braking unit. The SPJ2 spindle driver does not have a shorting piece connected at the factory. The SPJ2 spindle driver also uses a braking unit. 6. Input/Output Signal Connection In the connection of the NC system, the connection of input/output signals is the most prone to problems. Incorrectly connected output signals will burn out the basic I/O board. The connection method of input/output signals depends on the model of the basic I/O and remote I/O used. As shown in Table 1. (1) In each unit, the input signal can be connected in either source or sink mode. When using source mode, the COM terminal of CF31/CF32 is connected to 0V. When using sink mode, the COM terminal of CF31/CF32 is connected to DC24V. (2) For output signals, special attention must be paid: the connection method is determined by the model of the basic I/O and remote I/O. It cannot be changed. If the power supply or parallel diode in the output signal is connected in the wrong direction, the basic I/O and remote I/O will be burned. Customers who are using Mitsubishi NC for the first time often experience accidents due to incorrect connection of the output signal, resulting in the burning of the basic I/O and remote I/O. Source mode and sink mode are shown in Figure 3. (3) Connection of limit switches and origin switches All limit switches and origin signals must be connected as normally closed contacts. If the limit switches are not connected as normally closed, the NC system will alarm. When the origin signal is open, the NC system will consider it to have returned to the origin detection position and will run at the crawling speed. 7 Hardware Settings After the system connection check is completed, the hardware must be configured. 7.1 Servo Driver Axis Number Setting The axis number setting rule is to set sequentially starting from axis 1, as shown in Table 2. If a spindle driver is connected, it should also be set sequentially. For example, if a system has 3 servo axes and 1 spindle, the axis number sequence is 0, 1, 2, 3. Note: Axis number setting starts from "0". 7.2 Power Supply Unit Setting For systems using C1-CV type power supplies, the power supply unit must be set. Like the driver, the power supply unit also has a knob; turning the knob allows for setting. The power supply unit setting is shown in the table below. "Electromagnetic Contactor" refers to whether to use the "MC1" contact on the C1-CV power supply unit to control the main contactor coil. Generally, the "MC1" contact is not used. 7.3 Remote I/O Station Number Setting Remote I/O is more accurately called "Extended I/O". Remote I/O modules are used only when the system's input/output points are insufficient. Since the number and connection locations of remote I/O modules vary, their station numbers must be set. Each remote I/O hardware has a knob for setting the station number. The rules for setting the station number are: (1) When a remote I/O module is connected to a basic I/O, since the basic I/O has already occupied station numbers "0" and "1", the station numbers of the remote I/O are "2", "3", "4", "5", etc., depending on the order of connection with the basic I/O. Its address number starts from X40 and Y40. (2) When a remote I/O module is connected to a controller or display, the station number does not need to be set. However, its address number starts from X100 and Y100. (The following text appears to be a list of publications and is not translated: Proceedings of the 2nd Servo and Motion Control Forum, Proceedings of the 3rd Servo and Motion Control Forum)