Question:
Can the i700 supply module also be operated with a single-phase mains connection,
with connection between one phase and neutral (L1, N) or between two phases (L1, L2)?
Answer:
The mains input in the i700 supply module essentially consists of a passive B6 bridge rectifier. The supply module does not contain any active control for charging current limitation. The charging current is therefore limited in the respective axis modules.
The i700 supply module does not contain any monitoring for the level of the mains voltage and the presence of all mains phases. The single-phase mains connection is therefore not prevented by the response of a mains monitoring.
The single-phase mains connection is not specified by Lenze as an intended use.
If single-phase feeding is nevertheless to be used, this must be taken into account in the design by derating the power in order to minimise the risk of damage to the components:
- Derating: Reduction of the actual grid feed-in power to a maximum of 40% of the rated power.
Background:
- In the case of single-phase mains connection, the current flow is only via a part of the bridge rectifier in the mains input, so that this cannot be fully utilised in terms of power.
- Furthermore, the voltage ripple of the DC voltage increases considerably with only single-phase feed-in (2-pulse) instead of 3-phase feed-in (6-pulse). As a result, the DC link electrolytic capacitors are subject to a higher alternating load, which means that faster ageing can be assumed.
Aspects for operation with lower DC voltage:
- For the i700 supply modules, a smaller mains voltage is in principle not a problem. The achievable power must be set correspondingly lower than the specified rated power (voltage lower and maximum current the same).
- The switching threshold for the brake chopper in the supply module remains at 765V DC. The connected motors must therefore be designed for operation with higher voltage in terms of insulation.
In the axis modules, the undervoltage threshold (LU) must be reduced accordingly for operation on lower mains or DC voltage.
If the units are subsequently operated again on a mains with high voltage, it is essential to raise the LU threshold again.
Otherwise, the mains fuses may be triggered or the unit may malfunction in the event of brief interruptions to the mains supply, because the charging current limitation may be activated too late and a very high recharging current may then occur due to the large voltage swing.
CE/UL conformity, EMC:
- Lenze cannot certify CE conformity for single-phase operation, as compliance with conducted EMC emissions has only been proven for 3-phase operation.
It is therefore up to the end user to prove the conformity with regard to EMC, to realise it through appropriate measurements and, if necessary, a suitable filter design.
- The existing UL declaration of conformity describes three-phase operation, whereby no exclusions are formulated. It will therefore depend on the respective UL inspector whether single-phase operation is considered to be included.
Search terms: 1-phase, two-phase, 230V(AC)
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