Measurement Computing StrainBook/616 - Manual (Page 113)

Connecting the System to Power
CAUTION
An incorrect use of power can damage equipment or degrade performance. Prior to
connecting your devices to power, calculate your system’s power requirements.
If you assign one TR-40U per device your system’s power needs will be met and you
will not need to make power requirement calculations. However, such calculations are
required if you intend to “power daisy-chain” units, or have a critical battery runtime.
Each StrainBook/616 and Expansion Module is shipped with a TR-40U power adapter, which converts AC
power to +10 to +30 VDC power. The adapter’s DIN5 connector connects to the device’s mating POWER
IN DIN5. The other end of the adapter connects to a standard AC power outlet.
It is often possible to create a power daisy-chain. For example, a WBK16’s POWER OUT connector
could be connected to the next module’s POWER IN, providing that current limit will not be exceeded.
Note that TR-40U power supplies distributed today have a limit of 3.33 amp @ 15 VDC. Some earlier TR-
40U models have a limit of 2.7 A @ 15 VDC. Both values are more limiting than the 5 amp max limit of
the DIN5 connectors and the CA-115 power cables used for power daisy-chains.
Daisy-chaining power may result in inadequate power. For this reason, you need to know your system’s
power requirement. Computing power use is also important when using batteries to power modules, as you
will need to know a safe runtime before recharging is required.
The following statements relate to system power. They should be reviewed before
proceeding.
• Higher voltages draw fewer Amps for the same power.
Remember: Watts = voltage x current (W = V*I).
• The TR-40U power adapter provides power that is sufficient for the StrainBook/616
and the optional WBK16 modules, i.e, one TR-40U per unit. You do not need to
make power requirement calculations unless you intend to “power daisy-chain”
units, or you have a critical battery runtime. In other words, if you assign one
TR-40U per device your systems power needs will be met.
• Do not overload your power supplies. TR-40U power adapters are limited to
3.33 amps @ 15 VDC (2.7 amps @ 15 VDC if an early model). The best power
connection scenario is to use a single TR-40U for each unit in the system.
• Current drawn from other sources, such as car batteries, can be estimated from the
following Current Requirements table.
Use the following current requirements and worksheet tables to calculate your system’s total power
requirement. Take the appropriate amperage values from the first table to fill in the second table; then
perform the indicated multiplication and addition operations to calculate the amperage for all units in
your system.
StrainBook/616 User’s Manual 968594 System Expansion 10-9