Download Electricity Basics for Boiler Operation - Cleaver

TIP SHEET
Electricity Basics for Boiler Operation
The first law of thermodynamics states that energy cannot be created or destroyed, only transferred
and transformed. The building block of all matter is the atom, which is composed of a nucleus
made up of a balance of protons and neutrons. When an electron is knocked out of its orbit, which
is not that difficult, it is considered a free electron. When this occurs, the balance ends and the
atom becomes positive, seeking a negative replacement. So, essentially electricity is the flow of
electrons from more to less potential.
•
•
•
Energy cannot be created or
destroyed, only transferred or
transformed
On an electrical wiring diagram,
the circuiting sequence does not
read left to right, top to bottom
To ensure safety, proper training
is mandatory; seek out a handson course with a certified
instructor
AC vs. DC Power
The movement of electrons through a metal conductor (wire) is called current flow. Direct current
(DC) is unidirectional and cannot be transformed, so it’s not possible to boost its electromotive
force. This means that additional power stations would be required to get current to a plant facility.
Conversely, alternating current (AC) moves in both directions above and below the zero-volt
horizontal in a sinusoidal curve. It can be transformed to increase and decrease voltage. Voltage
is the electrical potential difference between two points and also referred to as electromotive force
(EMF). Because of its flexibility, AC power is the primary current supplier in the US.
There are many electrical definitions and concepts that are good to know.
Ampere. The flow of an electrical charge through 1 ohm by force of 1 volt.
Current. Electrical flow measured in amperes (amps).
Watt. The total power of a circuit at any given moment. [Volts x Amps = Watts]
Kilowatt. One thousand watts.
Hertz. Unit of frequency equaling one cycle per second (Hz).
Voltage. Electrical potential difference between two points and also referred to as electromotive
force (EMF).
Ohm. Resistance overcome by 1 volt pushing 1 amp.
Ohm’s Law. The electric potential difference between 2 points (voltage) is the product of the
current (amps) x resistance [E = I x R].
Single Phase. The distribution of alternating current where voltages vary in unison.
Three Phase (Polyphase). A means of distributing alternating-current electrical power; these
systems have three or more energized electrical conductors carrying alternating currents with a
definite time offset between the voltage waves in each conductor.
Ground. A direct physical connection to earth for safety purposes that should not carry current.
Neutral. Known as “common,” completes the circuit, allowing current to flow back and forth
within both neutral and hot wires.
A boiler’s electrical circuit consists of a number of devices. Here’s what they are and what they do.
Contactor. Controls electrical power to a device (normally a fractional horsepower motor) to
either establish or interrupt power in the circuit.
Starter. Powers and de-powers a motor of various horsepower. Unlike the contactor, it also
includes overload protection if the circuit overheats because of too much current draw,
breaking power and protecting the motor.
Relay. Electrically operated switch used when necessary to isolate a circuit or circuits
until it needs to be energized.
Timing switch. Used when there is a point in the operating sequence where a certain amount
of time must elapse before a function is called for, and a corresponding switch is made to allow
current to flow.
Electrical transformers. Can either increase or decrease alternating current. The examples
for reducing current are the 220/120 and the 120/24. The 10,000V transformer boosts the
voltage (e.g., an ignition transformer for lighting a pilot in a boiler).
Burner Management System (BMS). Automatically sequences the operation of the boiler’s
burner and safeties. Also called a programmer, flame safeguard or the boiler’s switchman.
Reading an electrical wiring diagram is not like reading a newspaper, where one typically reads
from left to right, top to bottom. The circuiting sequence can move all over the diagram, depending
on the sequence of the BMS. A schematic wiring diagram shows point-to-point connections,
but not the logic of the sequencing. The BMS provides the sequence for energizing the proper
circuits for safe and reliable boiler operation.
Unless operating personnel are properly trained, working with electricity and reading a wiring
diagram can be dangerous and costly, affecting both reliable uptime and personal safety as well.
Several organizations offer boiler operation and safety courses. The best training is one that
is hands-on with a certified instructor who has years of experience. To sign up for a course at
Cleaver-Brooks, visit Education & Training. To learn more about Basic Electricity Principles &
Boiler Wiring Fundamentals, watch this webinar.