Viessmann Vitotwin 300-W Installation And Service Instructions For Contractors page 134

Troubleshooting
Fault messages
Fault mes- Cause
sage
"305: Eng Generator current < 0.25 A
under cur- (20 s after connecting to the
rent" mains).
"306: Mains Generator voltage < 150 V
failure start (5 s after start pulse).
fault "
"307: En- Generator voltage < 50 V (if
gine stall" generator running).
"308: Stop Stop resistor test failed.
resistor in-
tegrity"
"309: Power Software fault, mains failure
fail detec- detection
tion"
"310: Power Electricity meter communica-
mon comm tion fault
fail"
"311: EGC Communication fault
comm fail-
ure"
134
(cont.)
Remedy
Check connecting cable be-
tween the control unit PCB
and the capacitor.
Check whether the circuit
breaker has tripped. Reset if
it has.
Remove both cables from the
capacitor and check the re-
sistance across the Stirling
generator. This must be at
least 4 Ω. Observe safety in-
structions on page 61.
If the fault recurs, notify
Viessmann Technical Serv-
ice.
Check cables between the
control unit and the resis-
tors.
Check that the cables are
plugged in correctly. See
connection and wiring dia-
gram (plug X100) on
page 161.
Check resistors, replace if
necessary (see page 151).
Check electrical installation
on site.
If the fault recurs, check ca-
ble harnesses and plug-in
contacts in the control unit
and power supply unit.
If the fault recurs or persists,
replace the control unit PCB
(see page 138).
Re-
set-
ting
SR
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