Introduction to Panel Meters

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Panel meters measure a range of electrical and electronic parameters.

Modern metering devices have become essential to hobbyists and professionals. These instruments ensure accurate measurement and display in the most demanding of environments.

Robust in design, metering devices are precision-engineered, and panel meters are no exception. Like with our grain moisture meter and light meter posts, here we will introduce you to panel meters.

Read on to learn the basics, including the two major types and how they work!

Panel Meters

Panel meters are an essential component that helps maintain equipment in many industries. These instruments display an input signal in either analogue or digital form.

The basic function of a panel meter is taking an input signal and converting it to a displayed value. A sample of voltage or current is taken from the signal, and a visual representation is created.

Voltage measurements are usually taken across the load. Whereas current measurements are in a series of configurations.

A common application of a panel meter is motor current monitoring. A motor that runs fans or pumps in an industrial setting will have specific line parameters.

For instance, the fan resistance may increase due to filter blockage. If not treated, this can lead to serious problems, such as a halt in operations.

Moreover, a broken belt can also lead to a drop-in motor output current. Experts recommend dealing with it immediately to regain productivity.

A potential or current transformer can be used to measure voltage and currents. This can then be displayed on a panel meter.

Check out our low current transformer units! They have a thermal fuse built into the primary winding for added safety. A variety of options are available to suit your specific needs.

Standard sizes

Panel meters are generally mounted inside an instrument panel. The panel must be cut to accommodate the panel meter. Most panel meters are designed to standard DIN sizes.

Display

A panel meter’s display has two types:

• Numeric: Displays only numbers.
• Alpha-numeric: Both numbers and letters can be displayed on the screen. This is suitable for complex signals.

Types of Panel Meters

There are two types of panel meters currently available in the market:

• Digital
• Analogue

1. Digital Panel Meters

Digital panel meters display the readings from the signal in a numerical form. Unlike analogue, digital is often distinguished by how it shows its readings. This makes it much easier for the user to track any minimal changes in the signal.

The signal comes from a sensor, whose input is converted into digital form. Then, it is displayed as a variable, such as temperature, pressure, etc.

This type of panel meter is ideal for smoothing out noisy signals. For one, it gives you a clear picture of your signal’s modulation.

Depending on their functionalities, digital meters can also act as controllers. They generate a control signal that drives an actuator, relay, safety gate, etc.

The main advantage of using one is its convenience and usability. It enables you to read the display from afar and even in dim or dark places.

LED displays consist of diodes that light up, usually following an N-segment algorithm. This boosts visibility in the dark.

Modern digital panel meters also have added features. This includes setpoints, alarms, and a data interface.

2. Analogue Panel Meters

Analogue panel meters feature a needle that swings back and forth. Best used in tracking and monitoring pulses in signals. In short, they display the values on a dial with a scale, pointer and needle.

This type of panel meter accepts a signal input. Depending on the model, it can also accept multiple signals like pulsating frequencies.

The introduction of the digital version reduced the prevalence of analogue panel meters. Even so, they still come in handy in various applications.

Further, analogue panel meters are available in more than one channel. They can measure multiple variables in different units, including three-phase power. Devices are also available that can measure radio frequency signals.

To select an analogue panel meter, you need to understand the meter’s mechanism. Two basic operation methods are available:

• Taut band: Commonly used in a rugged environment with high vibrations or shocks. A taut band is a moving pointer suspended between two ribbons of metal. It reduces friction and improves sensitivity.
• Pivot & jewels: They can also withstand high vibrations but are not as accurate as taut bands. The operation method involves a coil & pointer. Suspended by steel fitted into two jewel bearings.

Note: Pivot & jewel measures alternating current (AC). In contrast, the Taut band measures direct current (DC) measurement.

Have a look at the wide range of Panel Meters available from Wiltronics!

Applications Where You Need Panel Meters

Here are some common applications where panel meters come in handy.

1. Cooling water temperature

Injection moulding tools use pumped water to cool and solidify the plastic. The water flows through the tooling. Predictable cooling depends on both the temperature and flow rate.

A panel meter can display water temperature before and after it flows through the tool.

2. Motor current monitoring

Electric motors use fans in industrial dust collection equipment. If the fan resistance increases, this could signal a filter blockage.

A shunt or current transformer pulls the current down to a level the meter can accept.

3. Pressure monitoring

Brewing is a process where pressure monitoring is useful. During fermentation, it releases gas which could build up to risky levels.

A pressure sensor can send a current signal to a panel meter configured to display internal pressure. A digital unit with an alarm function ensures process operators are notified.

4. Welding current

Nondestructive verification of weld quality is challenging to perform. Thus, it’s essential to monitor welding parameters.

By using a shunt, it’s possible to bring down the current and voltage used at the welder. Plus, maintain to a level ideal to the panel meter, allowing it to act as a process meter.

5. Oven temperature monitoring

Many industries take advantage of continuous ovens. One of the applications is curing rubber products. The oven comes with preheat, curing and cool-down zones. Precise measurement of temperatures in each is essential.

Connect the temperature sensor to a panel meter and configure the device as a temperature meter. Set the alarm for when the temperature is outside the target range – ideal for digital units.

The Bottom Line

Panel meters are exceedingly important and flexible tools for displaying essential process information. These devices are a boon to anyone designing and building factory automation or process control equipment.

And if your line of work involves monitoring and/or controlling equipment, invest in a panel meter!