CSZ ZP 16, Installation, Operation & Maintenance Manual, Page: 58 / 88

OPERATION
Page 4-10
HIGH/LOW LIMIT CONTROL
If the chamber is operated with a live load (heat dissipating product), protection
should be provided. Provisions must be made to remove power from the product
being tested and from the chamber in the event the chamber temperature
exceeds safe limits for the product being tested. When testing a dead load (non-
heat dissipating product), protection need only remove power from the chamber.
The High/Low Limit Control shuts down the chamber and product under test
operation if the preset temperature limits are exceeded. Should the temperature
go beyond these limits, an audible alarm sounds and the chamber shuts down.
The Limit Control is a high and low limit control. It accepts an input from a single
Type "T" thermocouple to sense process temperature. An LED display provides
process temperature or limit set point information. Discrete LEDs tell the
operator the status of the unit. High and low limit set points are user selectable
at the front of the panel. The output device is a six amp mechanical relay.
The High/Low Limit Control incorporates auto power reset. In a non-limit
condition, auto power reset will automatically energize the output relay and
silence the audible alarm when power is applied. If a limit condition exists, the
output relay will latch in a de-energized state and the audible alarm will sound.
The output relay can be re-energized and the audible alarm silenced by the front
panel "Reset" switch being depressed one time only when the limit condition
no longer exists. The "Reset" should be depressed a second time to reset the
alarm.
The limit has three alarms that must be set up the same to energize all alarm
contacts at the same conditions. Alarm 1 shuts down the chamber. Alarm 2
sounds the audible alarm. Alarm 3 is used to de-energize the test product.
Proper operation of the High/Low Limit should be checked every three (3)
months.
VAISALA HMT337 HUMIDITY AND TEMPERATURE
TRANSMITTER (IF EQUIPPED)
The Vaisala HMT337 humidity transmitter is equipped with the “Warmed
Probe” and “Chemical Purge” options. The “Warmed Probe” feature prevents
condensation from occurring on the probe. The “Chemical Purge” feature
helps maintain measurement accuracy between calibration intervals. For
more information about the “Warmed Probe” feature, please reference the
HMT330 series user’s guide. For more information about the “Chemical Purge”
feature, please see the HMT330 series user’s guide.
This information is not
applicable to the Vaisala HMM100 series or any other humidity sensor.
PROGRAMMABLE DOOR LOCK (IF EQUIPPED)
The programmable door lock can be con fi gured to lock the chamber door at
certain temperature setpoints or in pro fi le steps. The setpoint values that trigger
the door to lock can be adjusted in the Settings Menu under Alarm Settings. The
“Setpoints” button in Alarm Settings provides a
fi eld to adjust the low and high
setpoints. These are the setpoints that will cause the door to lock. The user can
also modify if the alarm is silent or if it shuts down the chamber. The “Door Lock”
event can also be turned on or off within speci
fi c pro fi le steps like any other
chamber event.
A two amp alarm relay
contact is provided for
customer's use.
It is the
customer's responsibility
to interlock this control to the
test product power source
to de-energize the product
during an alarm condition.
The High/Low Limit Control
will also provide protection
from a malfunctioning
temperature control unit
and associated device.
WARNING
!
If the door lock is for
one speci
fi c application
(i.e. lock when blower is
on), it will not have these
programmable options.
NOTE