Electronic Oil Level Regulator

ELECTRONIC OIL LEVEL REGULATORS

Adequate oil level is an important requirement for long life of the compressor. Depending on the system design (eg. in rack applications) the correct oil level control under different operating conditions is pos- sible only using an active regulation system. The passive systems are problematic because they only operate satisfactorily under constant operating conditions, but due to seasonal variations this is not possible. Variations in operating conditions and defrost cycles may be covered by an active oil regulation, ensuring reliable operation. Active systems monitor the oil level in compressors and generate an alarm for low oil level. Even without built-in compressor oil pump and oil differential pressure switch (for example, scroll compressor), the oil supply to the compressor can only be monitored with an active control.A Hall sensor and a built-in magnet in the float system measure the oil level in the compressor. Depending on the oil level and the consequent changes in magnetic field strength results in a variable voltage induced into the Sensor. This is evaluated by an electronic unit and accordingly, the LED’s and the solenoid valve will be actuated. If the oil level is in the alarm range (see operation), the COM switch- es with a delay time of 90 seconds the relays contact into the alarm state. This signal can be used to shut down the compressor or for data processing. During the alarm condition oil is permanently fed into the compressor, with the target to bring the oil level to normal. If successful, the alarm is reset.The installed software features a “Power on Logic”. During the first installation and power on of the oil controller the time delays for “Injection” and “alarm” are suppressed. This means a compressor having no oil at all, will result in an immediate injection of oil and at the same time switches into alarm. This is to avoid that such compressor does not run for the standard 90 sec. time delay until the alarm occurs.

ELECTRONIC LEVEL SENSORS

COML/H offers a simple and compact level monitoring system with an integrated alarm function. In case of an insufficient/ overfilled liquid level in a receiver (oil or refrigerant) an alarm signal will be generated. This ensures the reliable operation of the refrigeration system and avoids greater damage to the system components. A Hall-effect sensor and a built-in float magnet system measuring the liquid level. Depending on the position of the float and the resulting change in magnetic field strength creates a variable output voltage. This is evaluated by an electronic board and the LED’s will be driven accordingly. As soon the liquid level reaches the yellow zone the output Signal S will be switched on with a delay of 10 sec.

A further drop/rise of Level to the red alarm range causes the Relays switches with a delay time of 90 seconds into the alarm state. This signal can be used for data processing or shut down of the system. If a correct fluid level can be restored, the alarm and the signal (S) will be reset. 

To monitor the minimum level COML/H will be installed in the normal position.For monitoring the maximum level, the device is rotated by 180 ° for the installation (see Figure 1 on page 3). This means that one version can be used for both applications, minimum and maximum level control.

ELECTRONIC OIL LEVEL REGULATORS

COM Oil Management

The electronic oil level regulation system with alarm function and compressor shut-down. Flexible with a 24 VAC and a 230 VAC Version.

Product Highlights:

• Software feature “Power on Logic” with suppressed time  delays for injection and alarm during first installation.

• Sophisticated operating principle, stand-alone controller for oil supply with oil level sensor and solenoid valve.

• Optimized energy consumption by special design of solenoid Valve and coil

• High-precision sensor technology allows a very precise level detection.

• No incorrect measurements by foaming and dirty oil or incidence of light

• T-Version for 100% humidity (CO2 applications)

• Standard version compatible with hydrocarbon refrigerants (R290, R1270)

Operation

The oil sight glass is divided into ranges:

Normal oil level: 40-60% sight glass height,

Critical oil level: 25-40% sight glass height,

Alarm Level: from <25% sight glass height.

If the green LED is on the COM is in operation and the oil level is with- in normal range. If the oil level for longer than 10 seconds is below the normal range, the solenoid valve is switched on, so that oil can be filled up to 60% sight glass height (maximum filling height). The valve closes again. The time delay of 10 seconds may be useful for certain types of compressors and applications since during the start of the compressor oil level varies and without a delay the filling of oil would start although enough oil is present. With this delay an overfilling of the compressor can be avoided.

If the oil level in a low pressure system in spite of active oil filling moves into the “critical area”, this could be a result of a compressor throwing more oil into the system than the COM can re-fill. In such a case, the differential pressure (oil pressure minus suction pressure) has to be increased to such an extent that sufficient oil can flow back. This can be achieved by the use of an ORV valve that is available with 1,5/3,5 and 5 bar differential pressure.To avoid oil shortage DEKA Controls recommends to leave the COM in operation even during compressor is in off condition.

ELECTRONIC LEVEL SENSORS

COML/H Oil Management

Electronic Liquid Level Sensor COML/H with alarm function and separate Output signal. Flexible with a 24 VAC and a 230 VAC version.

Product highlights:

• Sophisticated operating principle, stand-alone liquid level sensor,

• High-precision sensor technology allows a very precise level detection,

• No incorrect measurement by foaming and dirty oil/refriger- ant or incidence of light

• 2 separate outputs: Alarm + sensor output to switch an actuator, 

• Conforms to CE, EAC,

• Protection class IP 65, electrical connection with molded plugs and cable,

• T-models (COML-24-T) for up to 100% humidity