9 Disconnecting the Inverter from Voltage Sources
Prior to performing any work on the inverter, always disconnect it from all voltage sources as
described in this section. Always adhere to the prescribed sequence.
Damage to the seal of the enclosure lids in subfreezing
If you open the upper and lower enclosure lids in subfreezing conditions, the enclosure's seal can
be damaged. This can lead to moisture entering the inverter.
• Do not open the inverter at ambient temperatures lower than -5°C.
• If a layer of ice has formed on the seal of the lid in sub-zero conditions, remove it prior to
opening the enclosure lids of the inverter (e.g. by melting the ice with warm air). Observe the
applicable safety regulations.
Destruction of the measuring device due to overvoltage
• Only use measuring devices with a DC input voltage range of 1,000 V or higher.
Procedure:
1. Disconnect the circuit breaker from all three line conductors and secure against reconnection.
2. Turn the DC load-break switch to the position
O
.
3. If the multifunction relay is used, switch off the load supply voltage, if necessary.
4. Wait until the LEDs have gone out and, if necessary, the load connected to the multifunction
relay is switched off.
5. Use a current clamp to ensure that no current is present in the DC cables.
6. Remove all six screws of the lower enclosure lid using an Allen key (AF 3), lift the enclosure lid
upwards from below and remove it.
9 Disconnecting the Inverter from Voltage Sources
SMA Solar Technology AG
Operating Manual
STP20-25TL-BE-en-10
34
