Siemens EK 726 Series Manual de Serviço descarregar pdf (Página 16)

TECHNICAL DESCRIPTION

MICROMASTER

MICROMASTER Vector

MIDIMASTER Vector

SIEMENS DA 64 – 2002/2003

Version D 2/2

2. TECHNICAL DESCRIPTION

MICROMASTER, MICROMASTER Vector and MIDIMASTER Vector

are a series of drive inverters which are designed to be directly

connected to the line supply. They are self-contained drive units which

include all of the components required for their operation.

Depending on the line supply voltages, outputs and required

functions, this series comprises three versions: MICROMASTER,

MICROMASTER Vector and MIDIMASTER Vector. The

MICROMASTER is the most favorably priced drive unit for basic

applications.

MICROMASTER has three sizes with degree of protection IP20. The

MICROMASTER Vector is, from the mechanical dimensions, identical to

the MICROMASTER, however it has a higher degree of functionality and

the sensorless vector control makes it ideally suited for applications

requiring high dynamic response. It has additional I/O and larger,

intelligent power end stages for additional overload requirements. The

MIDIMASTER Vector has the same functionality as the MICROMASTER

Vector, however it has an extended output range up to 75 kW (90 kW for

variable torque). As standard, it has degree of protection IP21 but is also

available with degree of protection IP56 (NEMA 4).

2.1 Power section

All of the drive inverters have fully integrated power end stages

which are mounted on highly efficient heatsinks. The heatsinks are

cooled using a fan controlled by software. De-rating is not required

for ambient temperatures up to 50 °C (40 °C for MIDIMASTER

Vector). This is due to the heat dissipation.

All of the drive units have an uncontrolled incoming rectifier, a

capacitor-buffered DC link as well as a pulse width modulated

inverter with IGBT transistors.

If a drive unit is connected to the line supply, the DC link is pre-charged

through resistors and a pre-charging relay.

This limits the inrush current. The voltage in the DC link is converted

into a pulsed voltage with a variable frequency amplitude using the

latest generation of low-loss IGBTs in conjunction with optimized

pulse patterns. This offers the following advantages:

· Lower inverter and motor losses

· Motor frequency range: 0 to 650 Hz

· Motor voltage range: 0 V to the line supply voltage

· Almost sinusoidal motor currents

· High motor utilization

· Quiet motor operation using pulse frequencies up to 16 kHz

· The drive inverter is protected against short-circuits and ground

faults

An OFF command is not sufficient to electrically isolate the drive

units from the line supply voltage. A suitable switching element must

be used upstream from the drive inverters in order to ensure safe,

reliable separation from the line supply.

Slow-acting line fuses can also be used for protection.

All of the MICROMASTER and MICROMASTER Vector drive units

(this is not possible for MIDIMASTER) can also be directly

connected to a pure DC supply with suitably dimensioned voltage

using the DC link connections provided.

MICROMASTER (MM12/2 up to MM300/2), designed for operation

with 3-phase 230 V line supplies can also be operated with 1-phase

230 V line supplies. All of the 1- and 3-phase 230 V MICROMASTER

can also be operated on a 2-phase 208 V line supply. (CAUTION: A

1- or 3-phase 230 V drive inverter will be destroyed if it is connected to a

3-phase 400 V line supply.)

2.1.1 Thermal protection and automatic reduction

of the pulse frequency

When the pulse frequency increases, the losses inside the power section

also increase and result in higher heatsink temperatures. When the drive

inverter is operated above the recommended ambient temperature,

generally the drive inverter shuts down (trips) due to an overtemperature

fault. In order to prevent such undesirable trips, MICRO/MIDIMASTER

Vector automatically reduces its pulse frequency (e.g. from 16 kHz to 8

kHz). The heatsink temperature then decreases and operation can be

continued without any interruption. If the load or the ambient temperature

subsequently decreases, the drive inverter first checks whether the pulse

frequency can be safely increased so that it can appropriately respond.

2.1.2 Fast current limiting

The fast current limiting (Fast Current Limit; FCL) is a cyclic

hardware current limiting which is integrated in the drive inverter. Its

threshold value is slightly below the threshold value for a software-

related overcurrent trip (F002). Incorrect or undesirable trips are

avoided thanks to a significantly faster response if suddenly loads

are applied or fast acceleration is demanded.

2.1.3 Operation on non-grounded line supplies

A grounded (TN) line supply is always recommended for

MICROMASTER & MIDIMASTER drive inverters.

The MICROMASTER series can be directly connected to a non-

grounded line supply. If one of the input phases is directly connected

to ground while the inverter is operational, it continues to run without

any consequential damage.

MICROMASTER/MICROMASTER Vector is shutdown with an

overcurrent alarm if one of the motor cables is short-circuited to

ground.

MIDIMASTER Vector can only be operated on IT line supplies if the

pulse frequency is reduced to 2kHz. The MIDIMASTER Vector (with

a 2 kHz pulse frequency) continues to operate if one of the motor

cables is short-circuited to ground. The drive inverter can be tripped

due to an overcurrent when operated at more than 40 Hz or is close

to being operated at full load. If two or more phases are short-

circuited to ground, the drive inverter always trips due to overcurrent.

2.1.4 Using residual-current protective devices

MICROMASTER and MICROMASTER Vector can be operated with

residual-current protective devices under the following conditions:

v 1-phase: A residual-current protective device with 300mA (type

A) is permissible

v 3-phase: A residual-current protective device with 300mA (type

B) must be used

v The neutral conductor of the line supply is grounded.

v Only one drive inverter is operated on one residual-current

protective device.

v The motor cables are no longer than 50m (shielded) or 100m

(non-shielded) (otherwise an output reactor is recommended).

v We do not recommend using residual-current protective devices

for supply voltages of 400-500V and pulse frequencies

exceeding 4 kHz.

1 2 ... 11 12 13 14 15 16 17 18 19 20 21 ... 119 120

Comentários a estes Manuais

Sem comentários

Siemens EK 726 Series Manual de Serviço Página 16

Comentários a estes Manuais

Manuais e produtos relacionados com Fogões Siemens EK 726 Series