Bird Technologies DA40 UHF Series-Manual - Manual (Page 20)

Bird Technologies
6
Thermal Interlock
All Digital Air loads are supplied with a passive, normally closed, snap
disk overtemperature thermoswitch. Normally closed, the switch opens
above the maximum safe load temperature, turning off the transmitter
power. Because dissipation of the heat generated by the RF power
depends upon forced air cooling, if airflow over the resistor array should
stop or be restricted the temperature in the RF chamber can rise beyond
a safe limit. The heat sensor will sense the change and actuate the
interlock switch to turn off the transmitter. The interlock system will
not permit re-operation of the transmitter until a lower, safe tempera-
ture in the RF housing is reached.
Line Power Interlock
Digital Air loads are equipped with a line power failure interlock to pro-
vide protection against the loss of AC power. The switch is a normally
closed relay. The switch opens if no line power is supplied to the load, the
breaker on the load is tripped, or the power switch on the load has been
turned off. When power is restored, the interlock will reset.