Thermal Knives Actuation Module - terma

Thermal Knives Actuation Module
SPACE
For the activation of spacecraft thermal knives a specific
Thermal Knives Actuation (TKA) Module is available. The
module provides drive voltage and selection matrix for
12 thermal knives.
The thermal knives activation is in general performed by a
dc/dc converter that when commanded generates a
regulated voltage to be fed to the thermal knife selected by
an output switch matrix.
The module interfaces to the Terma standard backplane
interface providing bus voltage and two independent
Command & Monitoring (CM) busses that can perform all
commanding and read all module telemetry.
The following steps are required for the module to activate a
thermal knife:
1. Separation switch input is open.
2. Arm switch to be activated via a High Level Command
(HLC).
3. Setting of the output switch matrix via CM bus
command.
4. Activation of drive voltage via CM bus command.
The module provides all telemetry needed to ensure and
monitor correct activation of the thermal knives.
Each TKA module is an autonomy function deriving its
internal supply voltages directly from the power bus.
References:
• Two modules onboard each of the four Galileo IOV
spacecrafts. The first two spacecrafts were launched in
October 2011.
Thermal Knives Actuation Module
Space Engineering and Knowledge

Specifications:
Dimensions (L x W x H)
Mass
Bus voltage range
Output voltage
Drive current capability
Output power capability
193 x 150 x 24 [mm]
457 gram
28 – 50 volt
20.5 volt
> 2.1 ampere
> 41 watt
Number of output selection switches 12
Idle consumption, all switches off
< 0.22 Watt
Thermal Knife Actuator
Bias = 1.7mA
20V
60 – 80 s
Main Bus
I
DC/DC Converter
I
V
Output Selection
#12
Identical to Equipment
Power Distribution LCL
Aux
Supply
Bias = 16V
#1
#2
On
Off
PWM
Control
Current Limitation
Ref
OVP
Identical to Heater
Power Distribution
Switch
On
12 outputs
S
C
R
S
F/F
S
Enable
S
All outputs
are deselected
C
#1
#2 #12
4 to 16
Selector
#13 #16
5V
C
S
10k
End of
Deployment
HLC Arm A
HLC Arm B
CMD/TM
Separation
Switch
CM Bus A
Dual
Bus I/F
CMD decoder
&
TM multiplexer
CM Bus B
Thermal Knives Actuation Module Functional Schematic
Terma A/S Space
www.terma.com