Johnson Controls P28 Serie Bedienungsanleitung

PSC9705
I
ntroduction
These oil protection controls are designed to
give protection against low net lube oil pressure
on pressure lubricated refrigeration
compressors. The controls measure the
pressure differential between the pressure
generated by the oil pump and the refrigerant
pressure at the crankcase. A built-in time delay
switch allows for pressure-pick up on start and
avoids nuisance shutdowns on pressure drops
of short duration during the running cycle.
D
escription
When the compressor is started, the time delay
switch is energised. If the net oil pressure does
not build up within the required time limit, the
time delay switch trips to stop the compressor.
If the net oil pressure rises within the required
time after the compressor starts, the time delay
switch is automatically de-energised and the
compressor continues to operate normally. If the
net oil pressure should drop below setting (scale
pointer) during the running cycle, the time delay
switch is energised and, unless the net oil
pressure returns to cut-in point within the time
delay period, the compressor will be shut down,
and have to be manual reset. The compressor
can never run longer than the predetermined
time on low oil pressure.
Controls are available only for manual reset after
cut-out.
Heavy duty pressure elements
Safety lock-out with trip-free
manual reset
Ambient compensated timing
Dust-tight Penn switch
© 2003 Johnson Controls Inc.
Order No. PD-P28-E
European Refrigeration Controls Catalogue
Series P28
Oil Protection Controls
Feature and Benefits
Withstand high overrun pressure
Override is not possible in the control function
Stable delay time during all ambient conditions
Prevents pollution of the contacts by
electrostatic influences
Catalog Section 6
Product Bulletin P28
Issue 07/03/2003
P
P28DP Oil Protection Control
(P) Setpoint adjusting cam
Catalogue Section 6