Cryo-con 24C - Control Loop Outputs; Table 12: Loop 1 Heater Output Ranges

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Cryo-con Model 24C Specifications, Features and Functions

Control Loop Outputs

Control Loop #1, Primary Heater Output

The Loop #1 heater output is a short circuit protected linear current source. This

output is heavily regulated and RFI filtered. External filters should not be necessary.

Automatic shutdown circuitry is provided that will protect the heater output stage from

excessive temperature. Here, the heater output will be turned off until the output

stage returns to its safe operating area, then the output will be returned to normal

operation.

Load resistance values of either 25 or 50 may be selected. Using a 25 load, the

heater will be automatically configured to have a compliance voltage of 25V. With a

50 load, the compliance voltage is 50V. In either case, the maximum output current

is 1.0A.

Range

Compliance Voltage

25 50

Full-Scale

Current

Max. Output Power

25 50

High

25V 50V 1.0A 25 Watts 50 Watts

Medium

25V 50V 0.333A 2.5 Watts 5.0 Watts

Low

25V 50V 0.100A 0.25 Watts 0.50 Watts

Table 12: Loop 1 Heater output ranges.

Take care to ensure that the proper load resistance is selected. Connection to a 25

load while a 50 is selected will result in overheating and eventual automatic heater

shutdown. Conversely, connection to a 50 load while setting a 25 load will result in

the dissipation of only one half of the indicated heater power in the load.

Load resistance and Full Scale Output Range are selected via the front panel, or any

of the remote interfaces.

Heater output power displays are based on the heater read-back circuitry which

measures output current independently of the actual heater circuitry. Thus, heater

fault conditions are detected and their corresponding alarms asserted.

i Note: Heater output displays are given as a percentage of

output power, not output current. In order to compute actual output

power, multiply this percentage by the full-scale power of the

selected range. However, to compute actual output current, you

must first take the square root of the percentage and then multiply

by the full-scale current.