Whenever the motor curr ent demand limit set point is r eac h ed, it activates a capa c it y
override, again wit h a 2-step process. E xceeding 110% of the ra ted load amps for mor e than 30
seconds will initiat e a safety shutdown.
The compressor h igh lift (surg e prevention) se t point will cause a capacity override as w ell.
When the surge prevent ion set point is reached, th e c ont roller normally will only hold the guide
vanes from opening. If s o equ ipped, the hot gas bypas s v alv e will open instead of holdi ng the
vanes.
High Discharge Temperature Control
If the discharge temper at ure increases above 200 F (93 C), the guide vanes are
proportionally open ed to increase gas flow th r oug h the compressor. If the leaving chilled water
temperature drops 5° F (2 .8 ° C) below the control point temperature, machine will enter the
recycle mode.
Click here fo r Table 3 — Pr otective Safe ty Limits and Co ntrol Settings
Click here f or Table 4 — Capacity Overr ides