International English | Getting Started |
4.3.1A Typical Installation
Control
Connections
EMERGENCY
STOP
Supply
INVERTERM
ISOLATOR | FUSE | CONTACTOR |
Figure | Typical Installation |
Supply | The supply may be either single or three phase, depending on the |
| inverter type. The recommended wire sizes are stated in the |
| manual. |
Isolator | An isolator is usually required for safety reasons. |
Circuit | The protection rating is based on the input current as stated in the |
Breaker | manual. The input current is higher than the output current because |
or Fuses. | the form factor of the current is high. Do not use fast acting circuit |
| breakers or semiconductor fuses. Motor Circuit Breakers are usually |
| recommended for use with inverters. |
| Inrush currents on the latest inverters are typically equal to, or less |
| than the full load current, so nuisance tripping is less of a problem. |
Contactor | A contactor, with an emergency stop function connected may be |
| required both for auxiliary control and safety isolation. Do not use |
| the contactor as a stop start function This will cause unnecessary |
| wear on the contactor and there will always be a slight delay while |
| the inverter initialises. Use the control terminals or push buttons to |
| do this. It is not permitted to use the Run/Stop control of the inverter |
| as an emergency stop function. It is not recommended to fit a |
| contactor between the output of inverter and the motor. |
Motor | As shown in previous diagrams, many motors, particularly at low |
| powers, are designed for low voltage (230 V) or high voltage (400 V) |
| operation. The voltage is usually selected by fitting links at the motor |
| terminals. Instructions for low voltage (star) connection or high |
| voltage (delta) connection are usually shown on the inside of the |
| terminal cover. Clearly an inverter with a low voltage single or three |
| phase input will produce a low voltage three phase output, and the |
| motor should be connected accordingly. See also section 3.3 |
MICROMASTER Applications Handbook | 19 |