Description; Introduction - Siemens Simovert P 6SE21 Series Operating Instructions Manual

SIMOVERT P 6SE21 Series Inverters

1. DESCRIPTION

WARNING
SIMOVERT P transistorised voltage–source inverters operate with high voltages.
Connection, commissioning and fault–finding should only be carried out by qualified personnel who
are fully conversant with the relevant documentation, installation regulations, etc.
Only permanently–wired input power connections are allowed. This equipment must be grounded
(IEC 536 Class 1, NEC and other applicable standards).
Safety Note:
Do not apply input power to the equipment when the plastic cover has been removed. Dangerous
voltages are present within the equipment which could cause serious injury or death if touched. After
removing mains power, always allow a minimum of five minutes for the internal capacitors to
discharge before removing the cover.
When the 3–phase mains input is protected by a current–operated earth–leakage breaker, the input
to the inverter must be isolated from the mains if the earth–leakage breaker is to operate effectively.
The dc–link capacitors remain charged to dangerous voltages for up to five minutes after the incoming
power has been switched off.
When the motor is not running, dangerous voltages are still present on the power input terminals AND
motor output terminals and also on the dc–link terminals.
Under certain set–up conditions, the inverter may restart automatically after an input power failure.

1.1 Introduction

SIMOVERT P inverters of the 6SE21 series are designed for low–loss speed control of three–phase motors. This is
achieved by rectifying input voltage to establish a dc link voltage, and modulating this link voltage with a three–phase
transistor bridge to produce a Pulse–Width Modulated (PWM) three–phase output voltage (see Figure 1) . The
inductance of the motor windings converts this PWM voltage to a sinusoidal motor current. By varying the frequency of
this sinusoidal current, the rotational speed of the motor is controlled without significantly affecting the losses in the
motor. The output frequency can be adjusted between 0 and 400 Hz.
Siemens plc 1995
English
Operating Instructions
G85139–A1615–U156–A
02.95
7