The Series 4120 is no longer available. Please see the SCR70 series as a possible
substitute or contact our Temperature Engineering department.
The OMEGA™ 4120 Series SCR Power Controller consists of a high efficiency heat sink system with a cooling fan option, an electronic power control card, and SCR power switching devices configured to switch two phases of a 3-phase ac power line (the third phase connects directly to the load via convenient feed-through bus bar). The heat sink and/or heat sink cooling fan assembly serves to remove the heat generated in the SCR’s and also provides a mounting location for the electronic power control card.
In a two-leg three-phase design, two pairs of SCR’s are connected in an inverse parallel configuration, and each device must be isolated electrically from the other devices. Therefore, the heat sink assembly consists of four electrically isolated heat sinks with one SCR mounted on each. The four heat sink sections are joined mechanically while maintaining high electrical isolation. An optional fan can be attached to the end of the assembly.
The electronic power control card contains the circuitry to perform the following functions. - Transform an input signal from an external controller into a time proportional ON-OFF signal to control the SCR’s. - Provide isolation up to 2000 Vac between control circuitry, power line and input - Generate zero cross over firing commands - Provide integral cycle phase currents to three-phase heater load - Provide SCR compatible drive signals
The SCR’s switch the power (as shown in the diagram on the following page) of a 3-phase delta load or a 3-phase ungrounded Wye load. One SCR of each pair conducts during the positive half cycle of the sine wave, while the other device conducts during the negative half cycle.
The control signal to the 4120 is field selectable. Input signal options are: 1. 4 to 20 mA into 251 ohm 2. 0 to 5 Vdc into 8 K ohm 3. 1 to 5 Vdc into 8 K ohm 4. 1/2 watt, 1000 ohm potentiometer
The 4 to 20 mA control signal could be provided by an OMEGA™ CN9141, CN9241 or CN2000, CN2010, CN5050, CN6070A Series Controller with "F" option or any other controller able to drive 20 mA into 250 ohm
The two voltage inputs offered permit additional application flexibility. The zero-based signal permits applications using a computer or other external zero-based device. The 1 to 5 volt signal input will permit the use of one OMEGA™ controller (see above) with 4 to 20 mA output to control multiple numbers of 4120’s used in a heater network. An appropriate sized resistor will develop the 1 to 5 Vdc signal from the 4 to 20 mA current signal that can be connected to 4120’s in parallel configuration. For specific additional application information, contact OMEGA.
For complete product specifications see the Related Links section at the bottom of this page.
† 所有金额以RMB显示 注: 4120 Series come complete with I2T fuses- and lug mounting hardware kits. Current ratings shown are based on ambient air temperature below the controller. Ratings for units with no fans are based on controller mounted vertically in still air. Ratings include effect of I2T fuse mounted to heat sink. Fuse sizes offered are for I2T protection of the SCR’s consistent with full load current rating at 25°C (77°F) for fan cooled models. These I2T fuses are not intended to protect cabling or loads and are instead based only on I2T ratings of SCR devices.
