Arroyo Instruments TECSource 5400 Series - Using the Voltage Output Limit; Voltage Limit Engagement Conditions

Page 42 · 5400 Series TECSource User’s Manual
If the current limit engages, the I
TE
Limit LED on the front panel will illuminate.
Operating at the current limit is common, especially when transitioning from one
temperature to another. There is no harm or danger to the TECSource when
operating in this condition.
Using the Voltage Limit
The TECSource 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 TECSource is a current output controller, and the voltage simply
goes to whatever voltage is required by the TEC. In fact, the voltage limit is a
relatively new feature to the Arroyo Instruments controllers because of its typical
lack of need. However, with the high output power of the 5400, some
applications can benefit from this capability. 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. 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 any danger to
TEC devices due to the relatively short duration of the over-voltage condition.
For the voltage limit to engage, the following conditions must be met:
 V Lim in the main menu is set to 1V or higher
 Enable V Lim is set to Yes in the Advanced Menu
 At least 25mA of TEC current
The last point is to ensure there is a sufficient current signal that can be used in
calculating the load impedance (and therefore limit the current to correctly limit
the voltage).
If the voltage limit engages, the V
TE
Limit LED on the front panel will illuminate.
The V
TE
Limit LED will also illuminate if the TECSource is operating at the
maximum output voltage available to the controller.
Operating at the voltage limit is common, especially when transitioning from one
temperature to another. There is no harm or danger to the TECSource when
operating in this condition.
V Lim will be hidden from the menu if Enable V Lim is set to No.