Schematics for Wind Turbines

Question 1

On an electrical schematic, which is the negative terminal and which is the positive terminal, A1 or A2?

Answer 1

A1 = (+) positive
A2 = (-) negative

Question 2

What state are electrical schematics always drawn in?

Answer 2

De-energized
Electrical schematics are always drawn in a powered off state.
Example: switches

Question 3

Is a open switch on or off?

Is a closed switch on or off?

Answer 3

Normally Open (NO) Switch = switched off without power
Normally Closed (NC) Switch = switched on when not powered thus allowing energy to flow (on)

Question 4

What is a circuit breaker?

Answer 4

Circuit Breaker – A switch that automatically interrupts power to a device in an over-powered current situation.

Question 5

What is a relay electrical device?

Answer 5

Relay – A signal actuated switching device
* Used for circuits
Can be AC or DC

Question 6

What is a contactor?

Answer 6

Contactor – Motor Starter
A signal actuated electro-magnetic switch used to apply power to a higher power device (heater, motor….).

Question 7

What is a “feedback signal” and how is it used?

Answer 7

Feedback Signal – A signal sent back to the controller to indicate status of a device.

Question 8

1) What is the positive connection of a contactor or relay coil?

2) What is the negative connection of a contactor or relay coil?

Answer 8

A1 is positive

A2 is negative

Question 9

Define NO & NC.

Answer 9

NO = Normally Open
(the contacts of the device are open with no power applied)

NC = Normally Closed
(the contacts of the device are closed with no power applied)

Question 10

What is the difference between a relay and a contactor?

Answer 10

Relay - Circuits
A signal actuated switching device to control circuits

Contactor – Motor Starter
A signal actuated electro-magnetic switch used to apply power to a higher power device like a heater, motor starter, etc. Can carry more power/heat

Question 11

Reading schematics is critical for what and what?

Answer 11

Schematics are critical in fault isolation and repair.

Question 12

Electrical schematics are alway shown in what energy state?

Answer 12

de-energized state
or
shelf state

• Note: The de-energized (or ‘shelf’) state is NOT the normal operating or un-faulted state.

Question 13

1) Schematic drawings are either ____ or____ types?

2) What do wind turbines use?

Answer 13

Functional (Single Line):
Show electrically equivalent wiring connections
or
Actual:
Show all of circuit wires

2)WTGS schematics are functional schematics.
They do not show as built wiring in all cases. Functional schematics show electrically equivalent wiring connections. If all wires and wire connections were shown the schematic would become difficult to read. Terminals may have multiple wires per terminal. Schematically represented as one wire. Power supply and return (ground) connections most often display this convention.

Question 14

What is the simplified type of schematic drawings?

Answer 14

• One Lind Drawing (Block Diagram): Good for reference, but should NOT be used for in-depth circuit analysis.

-

Question 15

What is a schematic?

Answer 15

A graphical representation of the connections between electrical components, modules and equipment in a system.

Question 16

A dashed lines in a schematic between devices indicates what?

Answer 16

Dashed Line = they are mechanically linked

Question 17

What are the two schematic labeling standards?

Answer 17

European schematics use a standard labeling convention.
&
U.S. Schematics follow different convention.

Question 18

What is the best type of drawing for planning what needs to happen during Hazardous Energy Control maintenance.

Answer 18

One Line Drawing

Question 19

When drawing a yaw circuit, what 4 devices are that are included and what phase concept does it demonstrate?

Answer 19

1 Circuit Breaker
2 Contactors
4 motor protection devices
4 motors
To make a 3 phase motor change from forward to reverse, the power in the connector switches from changes from 1 to 3 while 2 stays the same.

Question 20

What are the two best examples of an interlock circuit in a GE wind turbine?

Answer 20

• Yaw system
• Lubercating pump

Question 21

When navigating a schematic sheet what is found in these three spaces: __ / __ : __?

Answer 21

A / B : C
A) Section
B) Page/sheet #
C) Navigation bar (at top of sheets)

Question 22

1) The safety chain in a GE turbine schematic can be found at what two connectors?
2) Which one is uptown and which one down tower?

Answer 22

12K2 is uptower

8K1 is downtower

Question 23

What does it mean “the bit goes high”?

Answer 23

It is energized

Question 24

What are the 3 views in schematics for reversing contactors.

Answer 24

• Motor Connection View
• Coil View
• Auxiliary View

Question 25

What are the voltages of all power inputs into the slip ring?

Answer 25

690v
400v
230v
120v
24v

Question 26

What are BBM and MBM switches?

Answer 26

MBB = Make Before Break
Limit switch that make a connection before breaking the other. “… the transfer switch makes a connection to the new power source before breaking its connection to the old one. As there’s no gap between disconnection and connection, downstream loads receive continuous power throughout the transfer process.”

BBM = Break Before Make
Limit switch that breaks the connection before making another.
“An open transition is a “break before make” transfer. That is, the transfer switch breaks its connection to one power source before making a connection to the other.”