Combined Cycle Power Plants: FAQs

DS200NATOG3 circuit board from General Electric.  This board can be part of a combined cycle power plant's control system.
A DS200NATOG3 circuit board. This board can be used as part of a combined cycle power plant’s control system.

In this short blog post we’ll answer some of the most common questions about combined cycle power plants.

What is a combined cycle plant?

Power plants generate electricity by driving a generator rotor through connected turbines. Power plants use different ways to generate the force to turn turbine blades. A mechanical force from wind or water or energy capture from fuels like coal, diesel, natural gas, and uranium changing states turn the blades.

A combined-cycle plant is a kind of thermal power plant. It uses a combination of two cycles of different energy capture. The first cycle uses natural gas combustion, which drives the generator. The heat from this cycle is used to create steam. The steam is used in the second cycle to produce energy via a steam turbine before the steam condenses back into water.

Continue reading “Combined Cycle Power Plants: FAQs”

Hardware Comparison: Multilin 469 vs. Multilin 369

GE’s Multilin Motor Management Relays provide protection and monitoring for three-phase motors. They also provide protection for their associated mechanical systems.

Close up of a Multilin 369 Motor Management Relay.
GE Multilin 369 Motor Management Relay


The GE Multilin 369 Motor Management Relay Series is designed with customizable relays. The units can protect three-phase motors and also offer monitoring applications.

Functional Summary Multilin 369

  • Display: 40 Character, Alphanumeric LCD
  • Status Indicators: 4 Output LEDs. Service LED, 5 other LEDs
  • Keypad: 12-buttons, including Help Key.
  • Interface: RS-232 comm port, Baud rate 120 to 19200
  • Case: Corrosion and flame-retardent
  • Digital Inputs: standard
  • Analog Inputs: Available
  • Current inputs: standard
  • Ground CT inputs: standard
  • Ports: 3 x RS485, Baud rate 1200 to 19200
  • RTD Inputs: available
  • Profibus Port: available
  • Backspin detection: available
  • Fiber Optic Data Link: available
  • Voltage Inputs: available

Protective Functions Multilin 369

Motor protection including:

  • Standard phase overload curves
  • Programmable (custom) overload curves
  • current unbalance

Management functions including:

  • Pre-trip data, to 40 events
  • starts per hour
  • time between starts
  • mechanical stall and jam
  • statistical data
  • backspin detection
  • flash memory
  • power metering (optional)

Technical Specifications Multilin 369

  • Control power: LO = 20 to 60 VDC, 20 to 48 VAC at 50/60 Hz, HI= 50 to 300 VDC, 40 to 265 VAC at 50/60 Hz
  • Power: Nominal: 20 VA, Max 65 VA
  • Fuse: T 3.15 Amp H 250 V, Timelag high breaking capacity
  • Operating Range: -40 to +60 Celsius
  • Operating Range w/Profibus: +5 to +60 Celsius
  • Humidity: up to 95%, non-condensing
  • IP50
  • Overvoltage Cat. II

Close up of a GE 469 Multilin Motor Management Relay
GE Multilin 469 Motor Management Relay


The GE Multilin 469 Motor Management Relay is used to manage and protect motors of many HP ratings.

Functional Summary Multilin 469

  • Display: 40 Character, Alphanumeric LCD
  • Status Indicators: 6 Output LEDs, 8 Motor Status LEDs, 8 other LEDs
  • Keypad:Alphanumeric with Help button, plus +/- value keys. Message toggle keys. Enter, Menu, Escape, and Reset Key.
  • Interface: RS-232 comm port
  • Case: draw-out, IP40-X
  • Digital Inputs: 9 opto-isolated
  • Analog Current Inputs: specifications vary
  • Differential Current Inputs: Primary, 1 to 5000 A. Secondary, 1 A or 5A.
  • Ground CT inputs: Primary, 1 to 5000 A. Secondary, 1 A or 5 A.
  • Phase Current Inputs: Primary 1 to 5000 A. Secondary, 1 A or 5 A.
  • RTD Inputs: 3 wire RTD types
  • Voltage Inputs: 273 VAC full scale
  • Ports: 2 x RS485
  • Modbus: Modbus RTU/half-duplex
  • Ethernet: Available
  • DeviceNet: Available
  • Backspin detection: Restart Block can act as a backspin timer

Protective Functions Multilin 469

Motor protection including:

  • Overload Pickup using RTDs
  • Overload Curve
  • Short Circuit Trip
  • Ground Fault
  • Unbalance Alarming
  • Acceleration Trip
  • Stopped/Running Cooling Times
  • Stator and Bearing RTDs
  • Unbalance bias of thermal capacity and K factor
  • Hot/cold curve ratio

Management functions including:

  • Starts per hour
  • Time between Starts
  • Enable Start Inhibit
  • Mechanical jam
  • Remote Switch
  • Vibration & Pressure Switches
  • Remote Start/stop
  • Breaker failure

Technical Specifications Multilin 469

  • Control Power: LO = 20 to 60 VDC, 20 to 48 VAC at 48 to 62 Hz, HI= 90 to 300 VDC, 70 to 265 VAC at 48 to 62 Hz
  • Power: 45 VA (max) 25 VA (typical)
  • Fuse: 2.50 A 5 x 20 mm SLO-BLO HRC Littelfuse, high breaking capacity
  • Operating Range: -40 to +60 Celsius
  • Humidity: up to 90%, non-condensing
  • Altitude: up to 2000 m
  • Pollution degree: 2
  • IP: check case
  • Overvoltage: check case

Other differences you may want to consider. While the Multilin 369 can be used for small or medium induction motors and induction motors with a cyclic load, they cannot be used for large induction motors or induction motors via VFD as the 469 Multilin can. Additionally, the 469 offers synchronous motor protection that the 369 doesn’t have.

Also keep in mind the 469 has trip/close coil supervision. The 369 doesn’t offer that.

Both Multilin options are extremely versatile. Since they both offer a wide operating temperature range (-40 C to +60 C) they are suitable for a number of climate conditions. So even if your factory has to deal with Canadian cold or Australian heat, these motor management relays should work well inside its walls.

Have more questions? Se our GE Multilin FAQs blog.

Nearly 10K Manufacturing Jobs Added in March in 12 States

Despite a shrinking job market due to the COVID-19 pandemic, the manufacturing sector showed job growth in twelve states.

A person cutting metal.  Manufacturing jobs like this can pay well.
Despite the COVID-19 pandemic, US manufacturing jobs showed growth in twelve states.

Over 700,000 workers lost their jobs in March across all sectors of the economy; 34,000 of those were manufacturing jobs. While news of large manufacturing layoffs and furloughs like ones at GE and Boeing have sparked alarm about the strength of the industry as a whole, the U.S. Bureau of Labor Statistics shows manufacturing posting significantly less than 1% job loss across all states. Twelve states, including Alabama, Arizona, Connecticut, Florida, Idaho, Kansas, Louisana, New Jersey, North Dakota, Rhode Island, South Dakota, and Utah all posted gains in employment that totaled 9200 jobs during the month of March. Additionally, four states reported no job losses.

Data below is broken down by state and compared to February 2020 employment numbers. All data was sourced from the US Department of Labor Bureau of Labor Statistics.

Updated March employment numbers can be found in our next post regarding April unemployment. These numbers were updated and released by the BOL on May 22, 2020.

Manufacturing Jobs Data by State

StateFeb 2020March 2020change% change

District of Columbia1,4001,300-100-7.14%




New Hampshire71,20070,800-400-0.56%

New Jersey251,800252,7009000.36%
New Mexico28,80028,80000.00%
New York436,600435,800-800-0.18%
North Carolina476,700473,000-3,700-0.78%
North Dakota25,60025,7001000.39%

Rhode Island39,20039,5003000.77%

South Carolina258,400258,40000.00%
South Dakota43,40043,8004000.92%

West Virginia46,20045,800-400-0.87%

Puerto Rico75,30075,000-300-0.40%
Virgin Islands80080000.00%

A chart showing manufacturing job numbers by state.