Danotherm has developed very flat power resistors for moderate power brake applications in drive systems, braking a few hundreds of watts to few kilowatts during a short time.
The Bi-alpha is available in 3 sizes; Bi-Alpha 4, 5 and 6. Their nominal power is rated at 45W for size 4, 100W for size 5 and 175W for size 6. These values are valid for forced air cooling of 2m/s. By increasing the airspeed the nominal power can be increased. Because of its low profile height they can easily be mounted at the back side of an VFC (Voltage Frequency Converter).
The Bi-Alpha is a simple construction where the resistor wire is wounded on a mica substrate and insulated by mica sheets on both sides. This element is enclosed in a metal alloy housing made from aluminium and zinc. The Bi-Alpha resistors are a cost effective solution for small to medium power drive systems.
Connection leads are insulated with high temperature silicon, rated at 250°C. IP value for each size is IP50.
HSD / HSF are wirewound resistors on mica elements, fitted into a heatsink filled with a silicone rubber which is UL recognized up to a working temperature of 220°C. They are ideally suited as balancing resistors. HSD types have its terminals upwards (vertical) to the heatsink. HSF have its terminals parallel to the heatsink. Its nominal power depends on the heatsink temperature it is mounted on.
HSCC and HSAC are thick film resistors. for optimum cooling they must be mounted on a heatsink. Due to theri very low inductivity, these resistors are ideally suited as snubber or filter resistor in power electronic inverters. HSCC and HSAC are available in 470R and 24kR. Other values are available on request.
HSP resistors are thick film resistors in an aluminium housing. They are intended to be mounted on a heatsink to allow maximum dissipation. Thick film resistors have virtually no inductance and are therefore ideally suited for snubbers in switching circuits. HSP resistors have its connections parallel to the heatsink. HSV have its connections in vertical position. Thick film resistors can be produced with 15%, 3% or 1% tolerance on Ohmic values.
PR resistors are thick film resistors and are offered in two mechanical sizes. PR100 for 100W and PR250 / PR600 for 250 and 600W. These resistors must be mounted on a heatsink of sufficient size to allow the maximum dissipation. Thick film resistors have virtually no inductance. PR types can have a single or a double resistor in one housing. PR250 has optional high voltage connection terminals and can be used in systems with working voltage up to 5 kVAC .
* Heatsink cooled values
These resistors belong to the lower power ratings of the aluminium housed types. They are mostly used in DC-links for charging and de-charging and in small inverter drives systems as brake resistor. CCH can be mounted on a (water) cooled plate to increase the nominal power. The nominal power ranges from 100-570W when cooled by natural air. When mounted on a water cooled plate the nominal power ranges from 500W - 2500W.
Extruded aluminium housing provides superior heat conduction. Housing deep finned for maximum heat dissipation at natural or forced air convection. Gold anodized finish for maximum resistance to environmental conditions. Special thermosetting compound with high thermal conductivity. Winding designed to give maximum core coverage and uniformity for even heat dissipation. Core centerless ground for maximum winding uniformity. Marking at top surface for easy identification after mounting. Complete welded construction terminal to terminal.
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