Day, Evening, Later in the evening, Night

Protect PV.500_MH Operating Instructions

If the DC voltage continues to increase due to the sun's rays get- ting stronger and the mains voltage and mains frequency are with- in acceptable limits, a start-up attempt is made. During a start-up attempt, the inverter stack is switched on, thereby drawing power from the DC voltage that is present. Inverter output contactor K7 is open during a start-up attempt. If the load on the DC voltage caus- es it to collapse too dramatically during this start-up attempt, the inverter stack is switched off again and there is a delay until the next start-up attempt is made. If the DC voltage does not dip too significantly, inverter output contactor K7 closes and power is fed into the mains. The inverter is now in the "Operation" status.

Day:

During the course of the day, the inverter will remain in the "Opera- tion" status if the sun's rays are strong enough and no faults occur. Power is fed into the mains and inverter output contactor K7 is closed.

Evening:

As the sun goes down, the power fed into the mains decreases. If this power falls below a certain value for a certain time, the operat- ing conditions are no longer met. The inverter stack is switched off, inverter output contactor K7 opens and the unit switches to the "Waiting" status.

Once the "Waiting" status delay has elapsed, the unit switches back to "Waiting for feed conditions". Although the sun's rays are not as strong, the DC voltage might still be high enough for a suc- cessful start-up attempt with the inverter stack and inverter output contactor K7 being switched on again. However, because the sun's rays are not as strong, it is unlikely that the operating condi- tions will still be met in the "Operation" status. As a result, the equipment will switch back to the "Waiting" status once a delay has elapsed.

When the unit switches back to this status, the delay is extended until the unit switches back to the "Waiting for feed conditions" sta- tus.

The cyclic changes of status "Operation" -> "Waiting" -> "Waiting for feed conditions" -> "Operation" can take place several times depending on insolation, the time of year, location and other condi- tions (e.g. snow on the PV cells). So that inverter output contactor K7 is not overloaded by this cycle of changes, the "Waiting" status delay is extended every time the unit switches to this status.

This has very little effect on the energy fed in, because the low levels of insolation mean that hardly any energy is being generat- ed.

Later in the evening:

Levels of insolation continue to fall. As a result, the DC voltage drops again. If the DC voltage drops below a certain value for a certain time, no more start-up attempts are made. If the DC volt- age continues to drop, the unit switches to the "Night" status.

Night:

The equipment shuts down all possible loads so that as little ener- gy as possible is being consumed. The equipment remains in the "Night" status until the following morning.

80000043212 BAL

29 of 68