46
Hb
Heater Burnout Alarm:
If the heater’s operating current
falls below this setpoint, the heater break alarm output
relay is energized. This option is used in cases where
the PXW is controlling a bank of heaters wired in paral-
lel. A current transformer around the hot lead going to
the heater bank and connected to the controller is tied
with the controller’s output and senses the current used
by the heater bank. If one or more of the zones burnout,
resulting in cold spots, the current used by the defective
heater bank is reduced. By determining what the optimal
current and the optimal current minus one zone for the
heater bank is, the Heater Break Alarm setpoint can be
calculated and entered.
Setting Range: 0.0 to 50.0 amps.
Not indicated without the Heater Break Alarm option.
Not available on PXW4, or with 4-20 mA DC outputs.
Detection is made only on a single-phase heater. This
function cannot be used when controlling a heater with
SCR phase-angle control.
Cycle Time, “TC,” must be set at 6 secs. or higher.
Refer to Appendix C for more details.
Optimal Current of
Heater Bank
minus
Optimal Current of
Heater Bank
less One Zone
+
Optimal Current of
Heater Bank
less One Zone
Heater
Break
Alarm
Setpoint
=
2
