TA Instruments DHR Series Getting Started Manual page 17

In the example below, the maximum sustainable cooling rate from 25 to -20°C is -3.87°C/min. So, even
though the Peltier plate can step from 25 to -20°C in just over 3 min, the fastest controlled ramp would take
almost 12 min (45/3.87).
Figure 9 Maximum sustainable cooling rate example.
DHR/AR Series Peltier Plate Getting Started Guide Page 17