Watlow ez-zone pm - Page 231

Watlow EZ-ZONE
®
PMI Controller • 227 • Chapter 11 Appendix
Indication Description Possible Cause(s) Corrective Action
Limit Low
Li.L1
Sensor input below
low limit set point
• Temperature is less than
limit set point
• Limit outputs latch and
require reset
• Incorrect alarm set point
• Check cause of under
temperature
• Clear limit
• Establish correct limit set
point
Limit High
Li.h1
Sensor input above
high limit set point
• Temperature is greater
than limit set point
• Limit outputs latch and
require reset
• Incorrect alarm set point
• Check cause of over tem-
perature
• Clear limit
• Establish correct limit set
point
Loop Open Er-
ror
Lp.o1
Lp.o2
Open Loop Detect is
active and the pro-
cess value did not
deviate by a user-
selected value in a
user specified pe-
riod with PID power
at 100%.
• Setting of Open Loop De-
tect Time incorrect
• Setting of Open Loop De-
tect Deviation incorrect
• Thermal loop is open
• Open Loop Detect func-
tion not required but ac-
tivated
• Set correct Open Loop
Detect Time for applica-
tion
• Set correct Open Loop
Deviation value for appli-
cation
• Determine cause of open
thermal loop: misplaced
sensors, load failure, loss
of power to load, etc.
• Deactivate Open Loop
Detect feature
Loop Reversed
Error
Lp.r1
Lp.r2
Open Loop Detect is
active and the pro-
cess value is head-
ed in the wrong
direction when the
output is activated
based on deviation
value and user-
selected value.
• Setting of Open Loop De-
tect Time incorrect
• Setting of Open Loop De-
tect Deviation incorrect
• Output programmed for
incorrect function
• Thermocouple sensor
wired in reverse polarity
• Set correct Open Loop
Detect Time for applica-
tion
• Set correct Open Loop
Deviation value for appli-
cation
• Set output function cor-
rectly
• Wire thermocouple cor-
rectly, (red wire is nega-
tive)
Ramping
rp1
rp2
Controller is ramp-
ing to new set point
• Ramping feature is acti-
vated
• Disable ramping feature if
not required