GUIDE TO CIRCUIT BREAKERS
Circuit breakers are not only great insurance for protecting your new motor, but they are also required by the Coast Guard for ungrounded current-carrying condutors. If a prop is caught on an underwater object (rock, log, thick weeds, etc) and prevented from rotating, the motor will respond by using more and more power from the battery in an attempt to turn the shaft. If this goes on for too long, the high level of current will permanently damage the motor, usually resulting in a completely totaled motor.
A trolling motor circuit breaker is designed to “trip” at a certain amperage, which breaks the circuit and prevents the motor from overloading and damaging itself. At between $20 and $40, they are significantly cheaper than purchasing a brand new motor! Circuit breakers come in varying amperages, and you want one that has an amperage rating (or amperage trip point) that is just above the amperage draw of your motor at max speed.
While small and medium trolling motors use a single 12v marine battery, larger trolling motors use larger 24v and 36v systems, and require 2 or 3 marine batteries, accordingly. These larger motors and multiple batteries are wired in a series pattern, and optimally, the circuit breaker should be wired within 4″ of your battery. Both the 24v and 36v trolling motor wiring diagrams are listed below along with the recommended circuit breaker. It is important to note you should never feed more voltage into a motor than what it is rated for (ie. never feed 24 volts into a 12v motor!).
Connecting Your Battery Charger
Onboard chargers are equipped with positive and negative leads for each battery. Simply wire each bank of the charger to each battery accordingly.
To avoid shorts, it’s always a good idea to keep the positive terminals covered with protective shields or proper electrical tape to prevent them from coming in contact with stray wiring, metal objects or other battery connections.
Guide to Low Voltage Circuit Breakers Standards
Low Voltage Circuit Breakers
This guide is intended as a practical guide for designers, specifiers and installers to enable them to specify low voltage circuit breakers in accordance with:
BS EN 60898-1,
BS EN 60898-2 and
BS EN 60947-2.
Miniature Circuit Breakers (MCB)
MCBs to BS EN 60898 are suitable for operation by ordinary persons and have fixed protection settings, generally a two position on/off operating handle and a performance relative to the final circuits in an electrical installation. They would normally be the final overcurrent protection measure in the electrical system, for example before sockets or lighting circuits.
Typical current ratings are from 0.5 A to 125 A. Short circuit ratings may be up to 25 kA. Performance and testing is in accordance with BS EN 60898 for domestic and similar applications categorised by the trip characteristic types B, C and D.
Moulded Case Circuit Breakers (MCCB)
MCCBs may have fixed or adjustable protection settings, normally a three position toggle operating handle giving on-off-tripped indication plus reset function, and a performance level relative to the incoming supply such that they can be installed at a point close to the supply transformer.
Air Circuit Breakers (ACB)
ACBs are normally used as the main incoming protection and have a spring-operated mechanism to open and close the device often charged by an internal motor.
Circuit breaker settings
Elasticsearch contains multiple circuit breakers used to prevent operations from causing an OutOfMemoryError. Each breaker specifies a limit for how much memory it can use. Additionally, there is a parent-level breaker that specifies the total amount of memory that can be used across all breakers.
Field data circuit breaker
The field data circuit breaker estimates the heap memory required to load a field into the field data cache. If loading the field would cause the cache to exceed a predefined memory limit, the circuit breaker stops the operation and returns an error.
Request circuit breaker
The request circuit breaker allows Elasticsearch to prevent per-request data structures (for example, memory used for calculating aggregations during a request) from exceeding a certain amount of memory.
In flight requests circuit breaker
The in flight requests circuit breaker allows Elasticsearch to limit the memory usage of all currently active incoming requests on transport or HTTP level from exceeding a certain amount of memory on a node. The memory usage is based on the content length of the request itself. This circuit breaker also considers that memory is not only needed for representing the raw request but also as a structured object which is reflected by default overhead.
Accounting requests circuit breaker
The accounting circuit breaker allows Elasticsearch to limit the memory usage of things held in memory that are not released when a request is completed. This includes things like the Lucene segment memory.
Circuit Breakers Information
Circuit breakers are automatic electrical switches designed to interrupt current flow in the event of an overload or short circuit.
Electrical circuits can experience several conditions which pose danger to associated equipment or the circuit itself, namely current overload and short circuits. An overload occurs when a larger than anticipated electric current flows through a circuit, generating excess heat and the possibility of a fire. Short circuits (which are a main cause of current overload) occur when current is allowed to travel along an unintended, low impedance path in the circuit, resulting in rapid heat buildup, explosions, and fire.
Fuses — which melt and “blow” in the presence of excess heat from overcurrent — offer effective circuit protection, but must be replaced after each circuit interruption occurs. Circuit breakers perform a similar circuit protection function but can be reset after each interruption and reused indefinitely.
Construction and Operation
Circuit breakers are typically electromechanical switches in which the circuit’s hot wire connects to both ends of the switch. When the switch is “on” electricity flows from the input terminal through the switch components and through the output terminal, completing the circuit. In the event of overcurrent the switch linkage breaks, interrupting the circuit.
When a circuit breaks, an operator must determine the source of the overcurrent and correct the problem. Overcurrent may be caused by introducing new devices into a circuit, causing an increase in the cumulative current and overloading the circuit; in this case simply removing the extra device would eliminate overcurrent. Circuit breakers are equipped with a manual actuator, so that an operator may easily reconnect the circuit and restart current flow after it has been interrupted.
What You Will Build
You will build a microservice application that uses the circuit breaker pattern to gracefully degrade functionality when a method call fails. Use of the Circuit Breaker pattern can let a microservice continue operating when a related service fails, preventing the failure from cascading and giving the failing service time to recover.
What You Need
About 15 minutes
A favorite text editor or IDE
JDK 1.8 or later
Gradle 4+ or Maven 3.2+
You can also import the code straight into your IDE:
Spring Tool Suite (STS)
How to complete this guide
Like most Spring Getting Started guides, you can start from scratch and complete each step or you can bypass basic setup steps that are already familiar to you. Either way, you end up with working code.
Starting with Spring Initializr
For all Spring applications, you should start with the Spring Initializr. The Initializr offers a fast way to pull in all the dependencies you need for an application and does a lot of the set up for you. This guide needs two applications. The first application (a simple bookstore site) needs only the Web dependency.
The second application (the reading application, which will use a Hystrix circuit breaker) needs the Web and Hystrix dependencies.