Lathe tutorial

Introduction

Controlling a lathe via a variable frequency drive necessitates an impulse command for both rotating directions and the stop position.

Choosing the inverter needs to be made according to the motor power and to the type of power supply available. To do this, you can check the article “How to choose your variable frequency drive.”

Note: It is possible to control a failsafe engine braking but also to inject direct current in the motor at the end of deceleration in order to immobilise the rotation shaft.

To execute the impulse control, you need to use pushbuttons. Two buttons having a NO contact (Normally Open) for the rotation direction as the model BPC_PBF_1NO sold by EASI-Spare. Concerning stop buttons, they must be equipped with a NC contact (Normally Closed) – BPC_PRC_1NC is a potential model.

Wiring

Power part

The inverter power supply is on the RT terminal on a single-phase inverter and on the RLT terminal on a three-phase inverter. Concerning the inverter protection, you can read the article “How to protect your variable frequency drive.” The motor is connected to UVW terminals at the inverter output. It is really important to not forget to connect the electrical bonding, commonly known as the Earth, to the motor and the inverter power supply.

Control part

The common of the three pushbuttons is directly connected to the COM terminal of the inverter.

The sens 1 contact output is connected to the DI1 input of the inverter; the sens 2 on the DI3 input and the stop on the DI2 input.

In case you are using an engine-braking, controlling it is made with a relay integrated in the inverter. The brake power supply arrives on the TC1 terminal and goes back on the TA1 terminal on the brake. This contact handles the brake switching on.

Note: according to the engine braking power, it is preferable to control the intensity it absorbed so as to not exceed the one that can handle the contact.

See the diagram below: