Heater Power Distribution Module - Terma

Heater Power Distribution ModuleSPACEFor distribution of bus power to spacecraft heaters aHeater Power Distribution (HPD) Module is available. Themodule provides sixteen output switches in two groupsof eight switches. Each group is protected by upstreamLatching Current Limiters (LCL).Each switch function can be commanded on / off via a dualcommand & monitoring bus, distributed by a backplaneinterface. The actual group load current and switch status isprovided as telemetry for each group of switches.In case of overload or short circuit, the output current isinstantly limited to protect the upstream main power bus.When exceeding a predefined delay the LCL willautomatically switch off.The voltage drop for each switch function is compatible withrequirements for a regulated 28 or 50 volt bus.Each heater switch group is fully self-contained with provenno failure propagation in-between, thus eliminating the needfor “A and B sides” in the distribution function. The moduleforms an autonomy function deriving its internal supplyvoltage directly from the power bus.The HPD module is 2 nd generation of an older 2 x 6 switchmodule with the following references:• 8 modules onboard XMM-Newton, flying sinceDecember 1999.• 12 modules onboard Integral, flying since October 2002.References:• Six modules onboard each of the four Galileo IOVspacecrafts. The first two spacecrafts were launched inOctober 2011.Heater Power Distribution ModuleSpace Engineering and Knowledge

Specifications:Dimensions (L x W x H)193 x 150 x 24 [mm]Mass477 gramBus voltage range28 – 50 voltNumber of heater switches 16Number of heater switch groups 2LCL load current class5.0 AmpereLCL trip off & current limitation level +5 % to +15 %Switch trip off delay5 msSwitch current regulation response< 500 nsSwitch voltage drop < 3%Module output power capabilityup to 400 WattIdle consumption, all switches off / on< 0.13 / 0.26 WattLoad current TM inaccuracy < 5 %Heater Power Distribution Module Functional SchematicTerma A/S Spacewww.terma.com