Arroyo Instruments TECPak 586 Series, Руководство пользователя

Страница: 19 / 40

586 TECPak User’s Manual · Page 19
TEC Control Modes
The
TECPak offers three TEC control modes: constant temperature mode (T
Mode), and constant resistance mode (R Mode), and constant current mode (Ite
Mode).
Changing the control mode is done using the TEC:MODE commands.
Constant temperature mode uses the sensor constants to calculate the
resistance of the thermistor at the desired or actual temperature.
While most users will only need the temperature control mode, the constant
resistance mode allows you to bypass the sensor equation and directly select
the sensor set point. This can be useful when only the desired sensor value is
known, or when the sensor-to-temperature conversion values are not available
for your sensor.
Using the Current Limit
The current limit in the
TECPak is used to limit the amount of current that is
delivered to the mount. Because the TECPak has a hardware current-controlled
output, the current will not exceed the limit at any time in any mode. Set the limit
by using the TEC:LIM:ITE command.
Operating at the current limit is common, especially when transitioning from one
temperature to another. There is no harm or danger to the
TECPak when
operating in this condition.
Using the Voltage Limit
The TECPak also supports a software-controlled voltage limit. In most
applications, the voltage limit is not needed, and can be left at the maximum
setting, as the
TECPak is a current output controller, and the voltage simply
goes to whatever voltage is required by the TEC. By default, the voltage limit is
set to the rating of the instrument plus 2 volts, so it will not engage unless
adjusted lower.
It is important to understand that the voltage limit is a
software-imposed limit,
which means that the response time to over-limit conditions can be several
hundred milliseconds or longer. During that response time, a significant over-
voltage condition can persist. However, with a properly set current limit, the
device is still protected from excessive power conditions, and should not pose