Coresense Protection - Vogt TUBE-ICE 03TA Service Manual

03TA Service Manual 9-9
SERVICE OPERATIONS
Sentronic Sensor (2D, 3D, 4D & 6D compressors before March 2011). The same oil pressure
sensor is used for all Sentronics. It mounts directly into the oil pump. The Sentronic sensor
measures oil pump differential pressure. It has an internal contact that opens on low oil pressure
and signals the Sentronic electronic control module to begin time out. The same contact closes
when proper oil pressure is present and stops the module time out. Should oil pressure fall below
7-9 PSID for a period of two minutes, the Sentronic module will open the control circuit, using
its Normally-Closed (N) contact, and shut the compressor off.
Approximate oil pressure can be measured in the field. Oil pumps are furnished with a Schrader
valve mounted on the oil pump discharge port. To measure oil pressure, subtract crankcase
pressure from discharge oil pressure. Tripping of the oil pressure safety switch is a warning that
the system has been without proper lubrication for too long a time. Repeated trips of the oil
pressure safety control are a clear indication that something in the system requires immediate
remedial action.
Sentronic Module (2D, 3D, 4D & 6D compressors before March 2011). The Sentronic has in
addition to the (N) contact, used for compressor shutdown, a Normally Open (N.O.) contact that
can be used in an alarm circuit. The Single Pole Double Throw (S.P.D.T.) contact of Sentronic
can be electrically isolated from the control circuit power supply, and used to control a circuit
with a different voltage. Sentronic has a timing circuit that actually compares the amount of time
with good oil pressure to that with insufficient oil pressure and has a memory that will shut the
compressor down after a period of more than two minutes if the compressor has a "history" of oil
pressure fluctuations with more unacceptable than acceptable pressures.
Sentronic also has a memory that retains the compressor oil pressure "history" for up to one
minute in the event of a power loss. Sentronic uses a permanent magnet integral with the reset
button to reset its output control relay in the event of a trip. When the reset button is depressed,
it magnetically pulls the Sentronic relay's armature to its original, reset position. Sentronic needs
no voltage present to reset.

Coresense Protection

Discus compressors manufactured after March 2011 will be supplied with CoreSense Protection.
CoreSense replaces the Sentronic Oil Pressure Safety Module on all Discus compressors and the
Electronic Motor Protector Module on 4D & 6D compressors. Note: 2D & 3D compressors will
continue to have Internal Line Break overload protection.
The oil pressure monitoring portion of the CoreSense will act very similar to the Sentronic Oil
Pressure Safety switch. A current transformer (CT) in the compressor junction box determines
when the compressor is running and starts monitoring oil pressure. Note: Wire "T1" passes
through CT before connecting to compressor terminal.
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