What is the Clamp Multimeter?

In this article I have discussed some of the Best Clamp Multimeter for HVAC. A new type of the meter that actually combines the clamp-on ammeter with a multimeter is called the Clamp Meter. It is also known as non-contact multimeter. The main difference between multimeter and clamp meter is that multimeter is connected physically for the measurements while clamp meter is clamped from the wire connected. By clamping we mean that there is one clamp which is opened first and it is passed through the wire from which we want to measure the current. It is then closed and meter gives the current reading that passes through the wire. It can measure several different electrical measurements like:

• Alternating Current Amperage (AC)
• DC and AC voltages
• Resistance
• Capacitance
• Frequency

The following figure shows the clamp meter. It can also be used as non contact voltage meter. Basically clamp meter is used for measuring higher currents (greaterĀ  than 10 amperes).

The price of clamp meter is quite reasonable and it is quite feasible for residential electrician as it can measure multiple parameters using a same device. The following figure shows how a clamp meter is connected for measuring current.

It can be seen for using this meter its jaws are clamped around one of the conductors that supplies power to the load. The magnetic fields of the wires are cancelled out if we clamp meter around more than one wires.

Such types of meters use current transformer for measuring currents. The jaw of the meter is actually the part of the core material of transformer. When the jaw is clamped around the wire, magnetic field of the current flowing through the wire induces voltages into the current transformer. The frequency and the strength of the magnetic field determine the amount of voltages induced in the current transformer. Since the frequency is fixed all around the country usually 60Hz, hence the voltages induced are directly proportional to the strength of the magnetic field.

These types of meters can have different range settings which are actually adjusted by changing the turn ratio of the secondary side. The ammeter is connected around the conductor which is actually the primary side of transformer. If we connect the ammeter around one wire on the primary, as shown in the figure above, the the turn ratio of primary is one as compared to the turn ratios of secondary.

The primary winding now has two turns instead of one, changing the transformer’s turns ratio. If two turns of wire are wrapped around the ammeter’s jaw as shown in the figure below:

In this case ammeter will show the double amount of current in the circuit. That is why we will have to divide the reading by factor 2 so that we can get the correct value of current.

For example, if the jaw of meter is clamped around two wires and meter shows 5A then the actual value is equal to 2.5A. Because of the ability of adjusting the turn rations, it is possible to calculate the low currents like in the control circuits.

Wrapping two rounds of wire around the jaw of the ammeter is only one method of altering the transformer’s turns ratio.
The ammeter’s jaw can have any number of wire turns wrapped around it, and the reading will be divided by that number. The reading will be divided by three if three turns of wire are wound around the meter’s jaw.

Fluke 902 FC True-rms HVAC Clamp Meter

Designed for HVAC workers to gather essential data, write reports, and cooperate with colleagues. The Fluke 902 FC True-rms HVAC Clamp Meter, a wireless Fluke Connect-capable meter, boosts HVAC technicians’ field productivity. The tough dual-rated CAT III, 600/CAT IV, 300 V meter conducts the necessary measurements of HVAC systems, including capacitance, contact temperature, resistance up to 60 kilohms, microamps for testing pilot light sensors, and resistance up to 60 kilohms.

Multiple tools are not needed with the 902 FC. The jaw fits wonderfully in confined work locations, and the tiny body makes it simple to hold.

The 902 FC can send measurements to a smartphone or tablet for in-depth analysis later on as a part of Fluke Connect, the broadest set of software and more than 40 wireless test tools in the industry. You can upload such measurements to the cloud.

In order to prepare and send reports from the worksite via email, technicians can combine measurement data from several Fluke Connect test tools. They can also work in real-time with other colleagues via ShareLive video chats or email while enhancing field productivity.

The 902 FC can send measurements to a smartphone or tablet for in-depth analysis later on as a part of Fluke Connect, the broadest set of software and more than 40 wireless test tools in the industry. You can upload such measurements to the cloud. In order to prepare and send reports from the worksite via email, technicians can combine measurement data from several Fluke Connect test tools. They can also work in real-time with other colleagues via ShareLive video chats or email while enhancing field productivity.

When working on high voltage/current panels, professionals are less likely to need to wear personal protection equipment thanks to the clamp metre. Simply close the panel, reenergize it, and then take measurements while remaining at a safe distance. To do this, simply turn off the panel, check that it is de-energized using conventional safety measures, insert the clamp, sync it to a smartphone with the Fluke Connect app, and then close the panel.

HVAC Clamp Meter CL440

• An automatically ranging TRMS (true root mean square) digital clamp meter is the CL440 HVAC Clamp Meter.
• Digital clamp measures inrush current and AC current of 600.0 A.
• 750V AC/600V DC voltage, DC microamps, resistance, continuity, frequency, duty-cycle, capacitance, and diode tests are all measured using test leads.

• Temperature measurements using a K-Type thermocouple range from -328 to 2462 degrees Fahrenheit (-200 to 1400 Degrees Celsius)
• Utilize the non-contact voltage tester built into the clamp jaw to detect AC current.
• Measurements of voltage and current can be viewed simultaneously on a backlit LCD with a dual V+A feature.
• CAT IV 600V, CAT III 750V, Class 2, Double Insulation safety rating, dedicated mode for recording DC micro amp and inrush current.
• For hands-free operation, utilize Magnetic Hanger Cat. No. 69417 (available separately).

Klein Tools CL800

• Clamp Meter for greater accuracy with automatically ranging true mean squared (TRMS) technology
• Test leads evaluate diodes and measure AC/DC voltage, resistance, continuity, frequency, and capacitance. Low Impedance (LoZ) mode of the thermocouple probe measures temperature and is used to locate and remove stray or ghost voltages.
• Class 2 safety rating with double insulation, CAT IV 600V, CAT III 1000V.
• Built to survive a drop of 6.6 feet (2 m).

• A battery compartment that is easily accessible and has a low battery indicator.
• Operating temperature: 32 to 104 degrees Fahrenheit (0-degree C to 40-degree C).
• Operating at a height of 6562 feet (2000m).
• Include batteries, a carrying pouch, test leads, and a thermocouple with an adapter.
• Satisfies specifications for use in basic and regulated electromagnetic environments, such as homes, offices, and light industrial settings.