Wiring Issues for Cartridge Heaters

In industry, cartridge heaters are usually utilized in groups of two or more. So, how to wire them to get the results you want is something to think about.

Let's first make two important points clear:

1. There are no positive and negative terminals on cartridge heaters.
A resistance wire, which is usually formed of nickel-chromium alloy, is the main heating element in a cartridge heater. Since it is a resistive part, it doesn't have a polarity.

2. The resistance of a cartridge heater stays the same.
Resistance = (Rated Voltage)² / Rated Power

(When designing a product, the rated voltage and power are set. From these two numbers, the resistance may be figured out.)

Actual Power = (Applied Voltage)² / Resistance

The user decides what the applied voltage is based on the formula above. Power output will change depending on the voltage. Using the wrong voltage could stop the heater from working as it was designed to, and in some situations, it could even cause an accident. So, always use the voltage that is listed on the heater's product label.

Here are some of the most frequent ways to wire heating elements:

1. Connection in a Series
A series connection is a simple way to link parts of a circuit. A series circuit is made by connecting cartridge heaters end-to-end and connecting the two ends of the chain to the power supply. In this kind of circuit, the current going through each heater is the same (Current = Total Voltage / Total Resistance of all heaters). When heaters with different resistances are connected in series, you may find the voltage across each one by multiplying the circuit current by that heater's resistance.

2. Connection in parallel
All of the cartridge heaters' starting ends are connected in a parallel connection, and all of their completing ends are connected. In this setup, the voltage across each heater is the same, but the current through each heater is different because of how much resistance it has.

3. Y-Connection (Star Connection)
The star connection is a way to wire three-phase AC power. Three-phase power is made up of three sinusoidal voltage sources that are connected in a certain way. They all have the same frequency and amplitude, but they are 120° out of phase with each other. In a star connection, the ends of the three heater sets are joined to make a common neutral point. From there, three terminals (U, V, and W) are drawn. The phase current and line current are the same here, and the phase voltage is the same as the line voltage divided by √3.

4. Delta Connection (Δ-Connection)
The delta connection is another way to wire three-phase AC power. In this arrangement, the heating elements are linked together in a closed loop, with the three connection points acting as the three phase lines. The delta connection doesn't have a neutral point or a neutral wire; it's a three-phase, three-wire arrangement. In this setup, the line voltage is the same as the phase voltage, and the line current is √3 times the phase current. When heaters with varying power ratings (and hence different resistances) are used in a three-phase delta connection, it gets hard to figure out currents and voltages.

Ordering Notes: Please let the salespeople or engineers know how you want to wire the products when you customize or choose them.

Important: Always connect the product to the right voltage for each heating element. Using a voltage that isn't rated will change the power output, could break the heater, and could cause accidents. Check the heater's rated voltage while wiring existing heaters in China, where the usual three-phase supply is 380V. Use a delta connection if the voltage is 380V and a star connection if it is 220V.