PROBLEM SOLVING
Mirage technical manual
page 61 of 65
Heating element
Every Mirage has a heating element that holds 3 resistor spirals. Single-phase machines use 2 of the
3 spirals in parallel connection, 3-phase machines use all 3 spirals where each spiral is connected to a
separate phase. Single-phase high power machines use 3 spirals in parallel connection but with each
spiral operated by its own solid state relay (see also previous section).
Figure P 6. Heating elements and mounting materials of a Triplette (top) and Duette (bottom). Note
shorter bolt for upper hole in flange; this bolt has inner threads to hold the element-cap bolt. The
Teflon ring can be replaced with an O-ring and spacer (see Figure P 9). Machines equipped with a
TRIAS (custom) element flange only need an O-ring as seal (no spacer, Teflon ring will NOT seal, see
Figure P 10).
The heating element of a Triplette has 3 spirals with a rating of 2000 Watt each, in a Duette, the
spirals are shorter and have a rating of 1600 Watt each (see Figure P 6). Each spiral has a
manufacturers tolerance of -10% / +5% and resistivity depends on temperature of and amount of
current through the spiral.
When you check the individual heating spirals of the element, they should have a resistance of 25-32
Ω (Triplette) or 32-40 Ω (Duette). A spiral with less resistance is short-circuited, a spiral with much
larger resistance has burned out. Table T 1 shows the values to be measured for different types of
machines.
Type
Power (Watts)
Resistance (Ohms)
Remark
Triplette
2000
25-32
Individual spiral
Duette
3200
15-20
Single-phase machine (2 spirals)
1600
32-40
Individual spiral
Table T 1. Resistance values for the different heating elements or individual heating spirals. Machine
is room temperature, measurements are made on heating element connectors.
Heating spiral short circuit
A heating spiral which causes a short circuit should be disconnected immediately as it will cause your
mains breaker to disengage the power and/or do damage to the solid state relay that it is connected
to. If only one spiral has a short circuit, you can rig your Mirage such that it will operate on the
remaining 2 heating spirals until you can change the heating element. You must disconnect both leads
of the failing spiral on the heating element itself since the short circuit will persist via the common
neutral (the right hand side connectors). A 4800W Duette or 6000W Triplette will of course miss 1/3
rd
of its heating power with one heating spiral disconnected, a 3200W Duette will operate normal with
one failing spiral disconnected and the “spare” spiral connected.
Heating spiral burn out
A burnt out spiral normally has infinite resistance such that there is no immediate need to disconnect it
but we recommend to do so anyway. The machine can operate (close to) normal on the remaining 2
heating spirals. Remove the appropriate bridge(s), connect the neutral of the 2 remaining spirals with
a self-made connection (2.5 -or more- mm
2
cable with 4 mm ring terminals).