|replacing a relay||or tumblers at electrictumblers.co.uk|
|HOW TO REPLACE A RELAY ON A PARAGON KILN|
Relays are switches. You can hear them clicking as they turn on and off, just like your light switch at home. But, unlike the light switch which typically switches 240V 0.5A, a kiln relay can switch anything up to 240V 30A. The much higher power means that the contacts will eventually corrode and oxidise until either they won't separate and turn off or they won't stay on. Fortunately, they're not expensive and easy to replace.
In the photo, the standard electro-mechanical relay has six terminals: one pair at one end and two pairs at the other. The low-voltage low-current pair at the far end connect to the programmer: usually by thin black and red wires. The high-voltage high-current pair in the middle connect to the mains: usually by thick black wires. The high-voltage high-current pair at the near end connect to the elements: usually by thick white wires.
When the programmer turns on the relay, an electro-mechanical switch inside the relay connects the mains to the elements. The activating current is not connected to the mains.
Don't work on your kiln on any surface that might get scratched. Unplug the kiln. Remove the screws that allow access to the interior of the kiln, or the control box. In the factory, screws are put in tightly with an electric screwdriver. When removing them, use the correct-size screwdriver. As with any screw, the wrong size screwdriver can damage the head, making it difficult to remove. And, when refitting them, don't over-tighten them in case the thread strips.
Don't just pull off all the wires on the old relay, imagining you'll remember where they go. Put the new and old side by side and swap one wire at a time If the wire tags are hard to pull off, use pliers: but pull on the tag, not the wire, in case the wire pulls out of the tag. Finally, check that the tags haven't got bent and are touching each other, and that the tags are fully pushed on and tight.
Other types of relay have been used so yours might look different, although most relays work in a similar way. Some need an input of 12V DC or 24V DC, and some have an output of 120V AC or 240V AC and are rated at 25A or 30A. Some kilns have more than one relay, either to share the load or because the kiln draws a high current.
|THE CHERRY HEAVEN MAINS TESTER SCREWDRIVER|
Mains voltage is AC, The mains tester screwdriver detects the mains, and allows you to follow it though the cables, the transformer, the relay, and the elements.
The mains tester screwdriver contains a current-limiting resistor and a small neon bulb. When the screwdriver tip touches AC mains and you touch the screwdriver's end cap, a tiny current earths through your body and the bulb lights.
It's rated for 220V-250V, has a 60mm blade, and a pocket clip. It's also just right for wiring plugs, fitting sockets, connecting lights, and wiring dimmers. The blade is particularly hard and durable.
|THE CHERRY HEAVEN DIGITAL MULTIMETER|
A multimeter allows you to make electrical measurements such as DC voltage, AC voltage, DC current, AC current, and resistance. To work on kilns, you don't need an elaborate multimeter.
It's important to understand what it is that you'll be measuring:
There are three commonly-used electrical measurements: Volts, for example 230V, is the pushing force. Amps, for example 10A, is the amount being pushed. And Watts, for example 75W, is the power. They're related by the simple formula Watts = Volts x Amps, usually written as W = VI.
Although EU voltage is nominally defined as 230V, UK mains voltage has a reliable average of around 240, which is used in calculations. For example: A regular UK 240 Volt 13 Amp mains socket can deliver 240 x 13 Watts, or 3120 Watts, usually called 3.12kW. It's interesting that a 10W radio will fill the room, a 100W lamp will light the room, and a 1000W heater will warm the room.
So, as we pay for electricity by the kilowatt, it's heating devices that cost the most to run. Which is why you get a big bill if you leave the heater on.
Riding an exercise bike casually only generates about 60W so, although it keeps you warm, you won't become energy-independent. Especially as most of a light bulb's energy is heat rather than light.
DC current, or direct current, flows in one direction so, with some small devices, such as a bedside alarm clock, the battery has to be the right way round. There are usually marks to show you which is positive and which is negative.
AC current, or alternating current, changes direction: 50 times a second in the UK. AC devices, such as your dish washer, usually have three wires: live, neutral, and earth. The way these function isn't quite as simple as it might seem, but briefly:
The live wire is connected directly to the generators of the electricity supply company. NEVER touch this wire, it carries 230-240 Volts and can kill you. The neutral wire returns the electricity to the generator after it has passed through your appliance, completing the circuit. The neutral wire is at approximately zero volts but to be safe you must NEVER touch this wire either. If the wiring is faulty it may be carrying the same electricity as the live wire. The earth wire is a safety measure and, usually, carries no electricity. However, if something in the appliance goes wrong, or it is wired incorrectly, then the earth wire may also be carrying the same electricity as the live wire. So, to be completely safe, NEVER touch this wire either.
Most multimeters are broadly the same: you set the range using a central dial. To measure voltage, such as the voltage across a heating element, the kiln has to be on. To measure resistance, such as the resistance of an heating element, the kiln should be off. The most important thing is not to let the leads touch anything other than the contact points you're testing.
It's ideal for servicing or repairing your kiln. You can check the mains voltage, the plug fuse, the kiln fuse, the transformer, the relay, and the elements. And you can test batteries, bulbs, cables, christmas lights, doorbells, fuses, power adapters, relays, switches, and wires, as well check most domestic electrical equipment.
They all come with instructions but, if you're not familiar with a multimeter, you can practise by checking the DC voltage of a torch battery, the resistance of a normal 13A fuse, and the resistance of a torch or mains bulb.
Some multimeters can check diodes and transistors, measure temperature, measure frequency, and hold the displayed result after you've taken the leads off.
You can buy one in the on-line shop. However, the photo is of a typical multimeter and the ones in stock may not look quite the same.
No one knows how long a device with its battery has been in warehouses or shops. Although they usually come with an economy battery, it might not last long or, worse still, it might be almost flat. Buy a spare straight away. And remember to turn the meter off after use.