Page 2848 - Din prodcuts 2020

20/50 ELECTRICAL INSTALL ATION SOLUTIONS FOR BUILDINGS 2CHC 420 001 C0201

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Automation boards
Ordering codes - SR2 enclosures

Temperature management
IP20 heater
Their use prevents condensation in the electric cabinets. They consist of a heating element
(PTC thermistor) inserted in an aluminium alloy ground plate. The PTC thermistor is a com-
ponent which modifies its impedance according to the operating temperature. It is intrinsi-
cally stable and ensures primary safety features for the heater and service stability.
The main qualities of the heaters using PTC are:
• electrical absorption (or dissipated power) which is almost constant in
• the range of power supply voltage between 100 and 250V;
• electrical absorption bound by inverse law to the trend of the ambient temperature.
The special tubular geometry of the ground plate allows efficient thermal exchange with the
heating element. This allows high powers and limited overall dimensions (especially in width
and depth); Snap-on assembly on 35 mm DIN rail. Requires a thermostat.

Dimensions Package/
(mm) No. of
Description H W D Code pieces
Anti-condensation heater 30W, 115 42 42 VA7930 1/1
110-240 Vac-dc
Anti-condensation heater 50W, 165 42 42 VA7950 1/1
110-240 Vac-dcc
Anti-condensation heater 75W, 210 42 42 VA7975 1/1
110-240 Vac-dc
Anti-condensation heater 100W, 165 42 51 VA7910 1/1
110-240 Vac-dc
Anti-condensation heater 150W, 146 82 51 VA7915 1/1
110-240 Vac-dc
Anti-condensation heater with fan 148 82 91 VA8300 1/1
300W, 230 Vac-dc

All the heaters with PTC absorb a higher power than the rated one on inrush according to
Detached, exposed
on all sides a transitory which lasts a few tenths of a second.
If the heaters are to be supplied by means of an auxiliary transformer, its apparent power
must be sized taking 1.5 times the rated power of the heaters with natural aeration and
For closed to a wall twice those with forced ventilation into consideration.
structures

IEC 890 method for calculating the effective cooling surface (CEI 17-43 method)
Left or right
exposed structure The total power dissipation P of an enclosure is linked to the exchange effective dissipating
surface S, the ∆T difference between the inner and outer temperature and the k coefficient
of heat exchange relative to the material of the enclosure:
Left or right closed P = k * ΔT * S
to a wall structure k = 5,5 for painted steel
ΔT = T1-T2;
T1 = dew point temperature (on overage 25 °C)
Central exposed T2 = minimum ambient temperature.
structure

Central closed to
a wall structure

20
Central closed to a wall
structure, with covered roof