5
TemperaTure ConTrol anD
limiTaTion
5.1 general rules
Pentair Thermal Management MI series heating cables are constant
power output heaters and as such typically require
temperature control, unless otherwise explicitly specified.
Good practice and local regulations may require additionally independent
temperature limitation devices; The selection of such devices also
depends on environmental conditions (non-haz or haz area).
For applications in hazardous areas either a stabilized design
or a thermostat control with temperature limiter complying with
the requirements of IEC 62086 and EN 50019:2000 can be used to
limit the surface temperature of the heating cable.
In cases where stabilized design is not applicable, a con-trol
thermostat must ensure that the heating system under normal
conditions will be switched off, as soon as maintain temperature
is reached.
An additional, independent temperature limiter ensures that
the surface temperature of the heating cable will not exceed the
maximum allowed temperature of hazardous area if the control
thermostat fails.
A lockout function ensures that the heating cable remains
switched off, until failure has been eliminated and normal
conditions are restored.
The lockout function is manually re-armed. Reset requires a tool
(e.g. a key to open a panel or a password for software).
Value of setpoint has to be secured against unintended change.
Limiter must permanently switch off in case of sensor
malfunction.
The limiter function is tested against relevant standards (e.g.
EN60730 or DIN3440 etc.).
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