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Ammonia Interter Drive Compressor iZN Series

Semi-hermetic type iZN Series

Semi-hermetic type

Open-type iZN Series



Innovative solution to help decrease global warming:
KOBELCO’s inverter drive ammonia screw compressor

Under pressure to reduce global warming, manufacturers are phasing out the use of HCFC as a compressor refrigerant. Even HFC refrigerant, which does not destroy the ozone layer, is designated as a chemical substance subject to emission reduction.

As the disuse of HCFCs moves forward, KOBELCO, which developed the world's first inverter screw compressor, introduces the iZN Series of screw refrigeration compressors.

The iZN Series use natural refrigerant NH3 (ammonia), which does not contribute to global warming. KOBELCO's well-established inverter control technology yields energy savings, while accelerating RPM technology. The KOBELCO iZN Series offers not only excellent Coefficient of Performance (COP), but also eco-friendly operation.

Ammonia inverter screw compressor series

Model Name Semi-hermetic type Open type
iZN40W iZN70W iZN80W iZN140W iZN160W iZN200
Moter ratings (kW) 24 37 45 37×2 45×2 100 125 135 180 250
- - - - -
- - -
Open Compressor
- - - - - - -

Full loader series

Model Name Open type
Moter ratings (kW) 220 315
Semi-Hermetic Condensing unit - -
Compressor unit - -
Open Compressor unit

* For the multiple driving system

Kobelco's six big features.

1. Outstanding energy-saving performance by Kobelco inverter drive compressor

The iZN series can control its cooling capacity with its inverter drive linear speed control to avoid excessive cooling, thereby permitting outstanding energy-saving performance.

A piston valve used for capacity control has been replaced to inverter drive capacity control to ensure optimum operation in accordance with cooling capacity fluctuation.

Outstanding energy saving performance according to partial loading

Saving merit per one year run

2. Maximum 40% increase in cooling capacity by accelerating rotating speed of inverter drive

(Compared with KOBELCO conventional model in 50Hz area)

patent registered No. 3950304 US Patent #6484522

Conventional refrigeration compressor has been unavoidable to reduce cooling capacity significantly accompany with evaporating temperature drops. Accelerating motor speed technology with inverter drive (Patent registered) enable iZN series increase its cooling capacity at lower temperature than -30°C.

The iZN series can perform equally in both of 50Hz and 60Hz area, which is a big merit for 50Hz area users where 20% less performance than 60Hz area has been unavoidable. Those functions enable to select smaller compressor than before.

When suction pressure saturation temperature is -40 cooling capacity is

iZN Series motor speed accelerates accompany with evaporating temperature drop.

Maximum 40% increasable cooling capacity by accelerating rotating speed by inverter drive

3. New iZ monitor with various functions for quick and advance trouble shooting

The New iZ monitor indicates compressor running conditions, various alarms and those histories. It also stops the compressor automatically in an emergency.

New iZ monitor

Alternative running applications
Alternative linear capacity control or step capacity control can be selected to meet clients' requirements.
Suction pressure / Remote temperature capacity control
Linear capacity control with originally equipped suction pressure sensor and also optionally installed temperature sensor (Supplied by user) at freezing site are available.
Additional indication
Super heat is added to monitor compressor conditions more clearly.
Linear capacity control
Linear capacity control mode enables automatic stepless changing of the rotating speed, with targeted values set for suction pressure and inside temperature.
Control is possible even with input of a 4-20mA DC signal from the sensor.
Step control
Capacity step control function is also equipped with iZ monitor. Its setting value is available to change flexibly.

Compressor protective functions

  • Discharge temperature
  • Oil pressure differential
  • Discharge pressure
  • Over current
  • Motor temperature

4. Merits of motor start-up by inverter drive

Merits of motor start up by inverter drive

Smooth motor startup by inveter drive eliminates inrush current and hot start

The effect of an inverter drive can be found when starting up a compressor, since conventional star-delta start-up induces inrush current and requires an approx 10-minute interval before restarting. Thanks to an inverter that allows smooth starting, the iZN series can restart quickly without any interval. The smooth starting mechanism permits the compressor to stop even when conventional conditions for interruption are not allowed. This mechanism enables more effective energy savings and downsizing of the power facility.

5. Multiple effects created by economizer and inverter drive harmony

The iZN series is equipped with an economizer regulate and control rotating speed at the 1st and 2nd stage of the inverter drive. If the 1st and 2nd stages do not change their rotating speed, economizer cannot perform properly because of pressure unbalance among the 1st , middle and 2nd stages. The iZN series can control rotating speed flexibly and perfectly to supply the best performance.

Multiple effects created by economizer and inverter drive harmony

6. Ammonia resistant motor with aluminum coil

* Semi-hermetic type only

Ammonia resistant motor with aluminum coil

What is a multiple compressor driving system?

A multiple compressor driving system can be implemented when a user needs the full capacity of two or more compressors. In this system, the compressors have similar freezing capacities.

Compressor running priority

  1. Inverter drive model No.1, serving as the capacity controller, starts running.
  2. When the freezing capacity of model No. 1 exceeds 100%, full load model No. 2 starts running.
  3. When the freezing capacities of models No.1 and No. 2 are more than 200%, full load model No. 3 starts running.

Compressors No. 2 and No. 3 may start in any order. In other words, after compressor No. 1 reaches full capacity, compressor No. 3 may start first, followed by compressor No. 2.

Compressor Models Capacity Control
Inverter Drive Model 0-100%
Full Load Model 100% only*

* Full Load Model has no capacity control devices with it.



Kobe Steel, Ltd.

International Marketing
Refrigeration System & Energy Department
Compressor Division Machinery Business


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