Lake Shore 350, User Manual

Page: 90 / 192

76 c
HAPTER
4: Operation
Model 350 Temperature Controller
Example 1: A 50
)
, 30 W heater is connected to Output 1.
Power Limit Voltage Compliance Limit
I = Squrt(P/R) I = 50 V/R
I = Squrt(30 W/50
)
) I = 50 V/ 50
)
I = 0.77 A I = 1 A
User Max Current should be set to the smaller of the two or 0.77 A. In this example,
the desired 30 W of power is available to the heater.
Example 2: A 75
)
, 50 W heater is connected to Output 1.
Power Limit Voltage Compliance Limit
I = Squrt(P/R) I = 50 V/R
I = Squrt(50 W/75
)
) I = 50 V/ 75
)
)
I = 0.81 A I = 0.66 A
User Max Current should be set to the smaller of the two or 0.66 A. In this example,
only 33 W of the desired 50 W of power is available to the heater.
To enter a User Max Current, first set the Heater Resistance setting to 25
)
for any
resistance less than 50
)
, or to 50
)
for any higher heater resistance. Set the Max Cur-
rent setting to User. The User Max Current setting now becomes available in the Out-
put Setup menu. Enter the calculated current limit value in the User Max Current
parameter.
User Max Current
Heater Resistance
Max Current 10
)
25
)
30
)
40
)
50
)
100
)
1.732 A 430 W 75 W x x x x
1.667 A (User) 28 W 69.5 W 83 W x x x
1.414 A 20 W 50 W 60 W x x x
1.25 A (User) 15 W 39 W 46 W 62.5 W x x
1 A 10 W 25 W 30 W 40 W 50 W x
0.707 A 5 W 12.5 W 15 W 20 W 25 W x
0.5 A (User) 2.5 W 6 W 7.5 W 10 W 12.5 W 25 W
Shaded black: Max current too high for these resistances due to voltage compliance limit
Bold: Discrete options available for 25
)
and 50
)
heaters under the Max Current setting
Menu Navigation:
Output Setup
Q
Output (1)
Q
User Max Current
Q
(0.1 A to 1.732 A)
Default:
User Max Current
Q
1.732 A
4.5.1.2 Power Up Enable
All configuration parameters of the Model 350 can be retained through a power cycle.
Some systems require that the Heater Range is turned off when power is restored. The
power up enable feature allows you to choose whether or not the heater range is
turned off each time the instrument power is cycled. Set the Power Up Enable param-
eter to Off to ensure that the heater range is turned off on power up. Set it to On to
return the Heater Range to its previous setting when power is restored.
Menu Navigation:
Output Setup
Q
Output (1, 2, 3, or 4)
Q
Power Up Enable
Q
(Off or On)
Default: Off
Interface Command:
OUTMODE
TABLE 4-14