Appendix; Electrical Connections - Riello 974 T Installation, Use And Maintenance Instructions

D867
NOTES
• Burners leave the factory preset for 400 V power supply.
If 230 V power supply is used, change the motor connection from star to delta and change the setting of the thermal cutout as well.
• The burners have been type-approved for intermittent operation.
This means they should compulsorily be stopped at least once every 24 houres to enable the control box to perform checks of its own effi-
ciency at start-up. Burner halts are normally provided for automatically by the boiler load control system.
• The burner is factory set for two-stage operation and it must therefore be connected to the TR remove control device to command light
oil valve V2.
Alternatively, if single stage operation is required, instead of control device TR install a jumper lead between terminals T6 and T8 of
connector X4.
ATTENTION:
!
- Do not invert the neutral with the phase in the electrical supply line. An inversion would lead to lockout due to ignition
failure.
- Replace the components only with original spare parts.

APPENDIX

Electrical connections

NOTES
The electrical wirings must be carried out in conform-
ity with the regulations in force in the countries of
destination, and by qualified personnel.
Riello S.p.A. cannot accept any responsibility for
modifications or connections other than those shown
in these diagrams.
Use flexible cables, in accordance with the regulation
EN 60 335-1.
All the cables to be connected to the burner must
pass through cable grommets.
The use of cable grommets can take various forms;
the following way is just one possible solution:
1 - Pg 11Three-phase power supply
2 - Pg 11Single-phase power supply
3 - Pg 9Control device TL
D465
4 - Pg 9Control device TR
ADJUSTMENT OF THERMAL CUTOUT
Used to avoid the burning of the motor owing to a strong increase
in the absorption, caused by the lack of a phase.
• If the motor is star-driven, 400V, the cursor must be positioned
on "MIN".
• If it is delta-driven, 230V, the cursor is positioned on "MAX".
If the scale of the thermal cutout does not include the absorption of
rating of the motor at 400V, the protection is guaranteed anyway.
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