APC MGE 6739380EN/JC User Manual download pdf (Page 12)

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Frequency converters with

redundancy

◗ the shutdown of one unit is of no

consequence for the load. The other

lines each take up an equal amount of

load power and the load continues to

be supplied normally;

Inverter shutdown results in the

following on the control panel of the

concerned unit:

◗◗ green "load protected" light 5 off,

◗◗ buzzer 1 on,

◗◗ red "load not protected" light 2 on.

Frequency converters without

redundancy

◗ in the event of a shutdown, the load

is no longer supplied with power;

◗ in the event of a major transient

overload (greater than 160% of the

rated load), the inverters will current

limit to 160% of their rated current for 1

second before stopping;

◗ in the event of a small but extended

overload (i.e. a continuous level of

power exceeding the full rated load),

the inverters will continue to supply

power for a period depending on the

magnitude of the overload (10 minutes

for a 125% overload, 1 minute for a

150% overload, see figure 17), and

then stop;

◗ in all three of the above cases,

inverter shutdown results in the

following on the control panel of the

concerned unit:

◗◗ green "load protected" light 5 off,

◗◗ buzzer 1 on,

◗◗ red "load not protected" light 2 on.

Output voltage quality and

continuity

The output voltage is stable in

amplitude and frequency and is free of

interruptions or transients outside

specified tolerances, irrespective of

Mains 1 or load disturbances (outages,

load step changes, etc.).

Steady state voltage regulation:

For stable or slowly varying load

conditions, the inverter output voltage is

regulated to within +/-0.5% in

amplitude.

The frequency of the output voltage can

theoretically be regulated to within

0.1% of the rated value, however the

output frequency range may be

intentionally extended to a maximum of

+/-2Hz so that the inverter can remain

synchronized with Mains 2 and its

inherent frequency fluctuations, thus

enabling transfer of the load to the

bypass line at any time.

Note:

The output frequency range can be

personalized and if necessary modified

on the customer site by a qualified

support technician from +/-0.25Hz

to +/-2Hz in 0.25Hz steps.

When the Mains 2 voltage moves

outside this frequency range, the

inverter is desynchronized and

operates in "free running" mode, with

the output frequency regulated to a

high level of accuracy by a quartz

oscillator.

When the Mains 2 frequency returns to

within the specified tolerances, the

inverter is gradually re-synchronized to

the bypass line at a rate of 0.5Hz to

2Hz/s (as per the value personalized by

the after-sales support department),

thus avoiding exposing the load to

sudden frequency variations.

Transient voltage regulation:

The inverter output voltage is not

notably affected by instantaneous

major variations in load characteristics.

This is due to the PWM (Pulse Width

Modulation) chopping technique and

the microprocessor-based regulation

system that instantly compensates for

any variation. In particular, the inverter

output voltage remains within +/-5% of

the rated voltage for load step changes

of 25 to 100% or of 100 to 25%.

Introduction (cont.)

Overload curve

Fig. 17

12345678910

(minutes)

1,5 In

1,35 In

1,25 In

1,15 In

1,10 In

1,05 In

30 120

◗ in the event of an overload, the

system only loses its redundancy as

long as the overload is less than the

total rated power of the functioning

units. If the overload is greater, the

operating mode is that previously

described for systems without

redundancy.

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APC MGE 6739380EN/JC User Manual Page 12

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