vacon • 24
Installation
Local contacts: https://www.danfoss.com/en/contact-us/contacts-list/
3.9
Grounding
3.9.1
Pole Grounding
It is prohibited to connect any pole, DC+ or DC-, of the photovoltaic system directly to PE.
3.9.2
Drive Grounding
All non-current-carrying metal parts (module frames, enclosures) and also the midpoint of the cur-
rent carrying conductors of the photovoltaic system must be connected to the PE of the drive.
3.10
AC grid connection
3.10.1
More than one source of supply
It is not recommended to supply the drive simultaneously from the photovoltaic cell and from grid.
3.10.2
Toggle between AC and DC
If both the DC input and the AC input are used (for example, when the energy from the photovoltaic
system is not sufficient), it is not allowed to switch directly between AC and DC supply. When switch-
ing from one supply to the other, it is mandatory to wait until the drive is discharged.
The minimum AC-DC switchover delay is 30 s for VACON
®
100 X MM4-MM6 and VACON
®
100 MR5-
MR6.
The minimum AC-DC switchover delay is 60 s for VACON
®
100 MR7-MR12.
3.10.3
Dual supply functionality
Sometimes a back up from the AC mains is needed in case the power from the photovoltaic supply
is not enough, for example, during night time and cloudy weather. The connection can be created in
several different ways. In this chapter, three alternative solutions are described.
Common safety related topic in every solution is to make sure that in case of possible malfunction
of drive there is no DC voltage connected into AC side. DC voltage from photovoltaic system can
make AC supply side parts energized having dangerous voltage, in case AC power is down. DC volt-
age can go very far distance wise into AC side, as far as galvanically possible. This can be very dan-
gerous especially during AC grid service. System must have a way to prevent this happening.
3.10.3.1
Changeover switch
Using a manually operated changeover switch is the most recommended way to make the switcho-
ver between AC and DC supply. In this case, a digital input can be programmed to select normal ref-
erence when using AC supply or MPPT when using DC supply. The changeover switch must have a
potential free auxiliary contact. See parameter P3.5.1.53 Mains Supply On. In case of a failure, the
changeover switch also prevents the DC voltage from going into the AC side.
3.10.3.2
AC and DC connected simultaneously without control
In this case, there is no possibility to have any control if AC or DC supply is used for energy source.
Supply always comes automatically from the source where the voltage is higher. Therefore, photo-
DANGER!
To completely isolate the equipment, use a two-pole disconnect switch for
the photovoltaic input (suitable for DC) and for the grid input (AC switch). Only one of
these switches is allowed to be on at a time. The delay time must be respected when
changing from one switch to the other.
Failure to follow these instructions can lead to death or serious injury.
DANGER!
If it is necessary to connect the drive simultaneously on AC and DC supply,
note that if the AC supply is lost, the drive must be separated from the AC supply grid.
Failure to follow these instructions can lead to death or serious injury.
