Steel grid resistors 3PS4 are a variation of the 3PS3 system, where two single elements are combined to one with double re-sistance and double power, this saves as-sembling parts and time, as well as volume for the resistor part.
Especially for fan cooled high power resis-tors this design may be a preferred choice, because a nearly quadratic cross section is easier to adapt to a round cross section of a fan.
The design is similar to 3PS3 resistors.
But only banks with side panels without protection grids are standardized, for use as build-in models for resistor units.
Four sizes up to 40 elements as single-strand resistors are available:
Size Number of elements Support bracket length
3PS46 26 725mm
3PS48 30 840mm
3PS49 36 960mm
3PS4X 40 960mm 1)
1) closer distance between elements
The resistors for natural cooling shall be installed horizontally such that the resistor elements are upright and the cooling air can rise freely between these elements.
Care must be taken, that the cooling air has unrestricted access from below and can freely leave the resistor at the top. The place of installation must have a good venting. In particular for indoor installation care must be taken that the ambient air does not heat up to temperature above 45°C.
The load values in the tables indicated for natural cooling and cause outlet tempera-tures up to 260°C. For outlet temperatures of max. 200°C the rating must be reduced by 25% (current value x 0.866).
The admissible loss
for three stacked resistor boxes is of about:
Size Admissible loss
3PS4 6 35,0 kW
3PS4 8 40,0 kW
3PS4 9 48,0 kW
3PS4 X 50,0 kW
Additional external venting with a fan may increase the rating and thus also the ad-missible load, in particular in the case of in-termittent operation with a high duty factor.
The resistors are maintenance-free. In case of strong dust formation, however, occasional cleaning with compressed air should be done to preserve the insulation against the grounded housing elements.
3PS4 (1)00 -(2)
3PS4 = System name
(1) = size:
6 = 26 elements
8 = 30 elements
9 = 36 elements
X = 40 elements
00 = protection class IP00
(2)= Ohm value int. usage, e.g. 40R8