Carbolite HTF 18 - Manual (Page 4)

MF47-3.05 4
2.4 Electrical Connections
Connection must be made by a competent person. A qualified electrician is recommended.
These models are designed only for single phase electrical supplies, or for two live phases and
neutral of a 3-phase supply. The furnace must be connected only to the type and voltage of supply
for which it was ordered, though some changes may be made as explained in section 2.5.
Check that the supply voltage is compatible with the voltage on the label, and that the current
capacity is sufficient for the amperage on the label, before connection to the supply. A table of the
most common ratings is given in section 8.1 of this manual.
Normally a supply cable is not fitted, and connection is to be made to terminal blocks accessed by
removal of the left-hand end side cover (see section 5.3). The supply cable must be properly
connected and fitted with an appropriate strain relief at the entry to the case.
The supply cable should be wired to an isolator or fitted with a line plug. The isolator must be
within easy reach of the operator, or the line plug must be easily removable and on a lead not
exceeding 3m length. The line plug must allow the protective earth (ground) to be connected
before the supply conductors and to be disconnected after them. The supply point must be marked
as the disconnecting device for the furnace.
The supply MUST incorporate an earth (ground).
CONNECTION DETAILS supply type
Supply Terminal label Cable colour Live-Neutral Reversible or Live-Live
1-phase L Brown to live to either power conductor
N Blue to neutral to the other power conductor
PE Green/Yellow to earth (ground) to earth (ground)
2-phase L1 Black to phase 1
L2 Black to phase 2
N Light Blue to neutral
PE Green/Yellow to earth (ground)
2.5 Voltage Differences
Each model is manufactured in one of the following voltage range varieties:
208V
220 to 240V
380 to 415V (not HTF 17/5 or HTF 18/4)
It is not possible to alter a furnace between the 380-415 range and either of the other ranges: there
are too many component differences.
It is possible to alter a furnace between 208 and 220-240, provided the thyristor unit is replaced. A
transformer tapping must also be altered. See sections 5.4 and 5.10.
It is possible to alter the voltage within one of the ranges above, by reconnecting the incoming
cable to the transformer to the appropriate primary tapping. The tappings are 208-220-230-240V,
or 380-400-415V, and are labelled on the primary side of the transformer – see section 5.10. It is
also necessary to adjust the setting of the thyristor stack: see section 5.4.
Examples:
- to alter a furnace made for a 240V supply to 208V: replace the thyristor stack, move a cable to
the 208V transformer tapping, and adjust the thyristor stack.
- to change from a supply of 220V to 230V: move a cable to the 230V tapping, and adjust the
thyristor stack.