HP 11744195 User Manual

Page 16

Chart Environmental Chambers

Operation

2. Control Power (OFF, ON)

This switch controls the 24vdc control power in the control system. If this switch is
turned OFF, all control functions will be disabled. The temperature controllers are
powered from a 115vac circuit, so they will remain powered up even if the control
power switch is turned OFF, however no heating, cooling, etc will be able to take
place.

3. Chamber Reset (push button)

This button will be illuminated under normal operation. If the Temperature Safety
controller goes into a high or low temperature alarm, this button will no longer be
illuminated. The respective heating or cooling action will not be enabled until the
alarm condition is no longer present and the Chamber Reset button has been pressed.

4. Air Safety (up, down; touch pad)

This controller is located inside the control box and is not to be adjusted by the
operator. The controller has pre-set alarm set points to protect the chamber from
thermal run-away and extreme temperature conditions.

5. SERIAL COMM (communications connection)

This connector is provided on the back of the control box for future serial
communications with the Watlow controller. The cable that is attached to this
connector is coiled up inside the control panel

CAUTION: If the chamber is left with the circulation fan running, and either no

temperature set point, or no liquid nitrogen supply, the internal chamber
temperature will rise. This rise in temperature could damage product inside
the chamber if it is not controlled.

The following graph shows the rise in internal chamber temperature with the circulation
fan running and no cooling output being applied. It is important to note that the
circulation fan does generate a small amount of heat, which causes the internal chamber
temperature to rise slightly from ambient to about 28°C. This data assumes the chamber
started at ambient temperature, there was no live heat generating product in the chamber,
and neither heat nor cool outputs are being applied.

If the RS-232 option is ordered, the cable will be installed to the controller.