Comparison Static UPS - Rotary UPS

Comparison between Dynamic and Static UPS systemItem Static – UPS Dynamic – UPS Result

Reliability Switches, rectifier and inverter extra in the

power-line converting the total power demand

Only three components in the power-

line from the mains to the load

50% higher reliability of the line-interactive diesel

UPS-system

Energy conversion Two times energy conversion No energy conversion Higher efficiency of the line-interactive diesel UPS-

system

Efficiency 92 % Approx. 97% Lower energy consumption during normal operation of

the interactive diesel UPS

Autonomy time Limited due to usage of batteries Unlimited because of usage of a diesel

engine

Diesel UPS-system always available

Total Harmonic distortion

(THD)

THD > 8% THD < 3% Due to the choke coil generator combination an

effective filter is created

THD filters Additional filters are necessary to reduce the

THD to an acceptable level

No additional filters Extra costs for filters with static UPS system

Power factor improvement No power factor improvement by the system Power factor improvement included in

the system. PF = 0,98 at mains side

Extra cost for static UPS for the power factor

improvement equipment

Load characteristics 1,5 x In

Output frequency +/- 5% during genset

operations

>10 x In

Output frequency within 1%

Selectivity of the diesel UPS-system is considerable

higher

Reduction of the energy costs

Peak-shaving Not possible Possible, optional Reduction of the energy costs

Installation space 100% 50% Savings in favour of diesel UPS system with regard to

the building costs (m2)

Air-conditioning Necessary for the battery-room and for de UPS-

system

Not necessary Extra costs for the Static UPS-sytem and higher

operational (yearly) energy cost

Life-time batteries Battery lifetime depends on the type and

quality. Lifetime between 3 to 8 years

Not applicable Depending on autonomy time requested, the re-

investment of the batteries every 3 to 8 years required

Lifetime UPS-system 10-15 years >25 years Lower depreciation cost for diesel UPS-system

Maintenance Higher maintenance due to combination of

static, batteries and a separate Genset

Maintenance reduced to a minimum

level due the line-interactive principal

Lower maintenance cost of diesel UPS-system

Investment Higher investment and operational cost Lower investment and approx. 25%

lower operational cost

Better price/performance for diesel UPS-system