Electronic ballasts, modern LED lighting, energy-saving lamps and power supplies typically have high inrush currents when switching, which can be up to 250 times the nominal current. ComatReleco offers special relays for high inrush currents:

• CHI14 / CHI34: Zero-crossing switching, up to 800A inrush current for 800us
• C7-W10: With tungsten pre-contact, up to 500A inrush current for 2.5ms
• C10-A15: With silver-tin oxide contact, up to 120A inrush current for 20ms
• CIM14: Time relay with zero-crossing switch, up to 800A inrush current for 800us

The series connection of a resistor and a capacitor causes the current to decay in a damped oscillation during the switch-off process. During the switch-on process, the resistor prevents the full capacitor charge from discharging via the switch contact. The protective circuit using an RC element is very well suited for alternating voltage. In addition, there is an immediate switch-off limitation.

A reliable three pole LED step switch can be implemented with the CHI34/UC24-240V together with the CIM1/UC24-240V. The CIM1 manages the step logic. The CHI34 is designed for modern LED systems and ensures stable switching of the lighting.

Coil voltage?

• Available coil voltages AC and DC can be found in the catalogue. ComatReleco's technical support team can help you if you cannot find a suitable coil voltage for your application.

Load to be switched?

• Type of load?
  • Is the load to be switched ohmic? Inductive? Capacitive? This is a very important factor to know when selecting a relay/contactor.
• AC? DC?
  • Is the load to be switched supplied with alternating current or direct current? How high is the voltage?

Switching frequency?

• How often should the relay be switched per day, hour, minute or even second? For many switching cycles, a semiconductor relay is recommended, as there is no mechanical contact and the service life is therefore practically infinite.

Environment?

• This includes, for example, the ambient temperature where the relay/contactor is installed. It also includes information about the environment: dusty? Does moisture penetrate? Aggressive gases? Other factors worth mentioning?

Switching small signals – what should be considered?

• If signals in the mA range are to be switched, it is important to select a suitable relay with an appropriate minimum load. Relays with gold-plated contacts are suitable for this purpose. Gold has very good conductivity, which is why small signals can be switched. However, gold tends to weld the contacts when currents are too high. ComatReleco also offers relays with double gold contacts. These double contacts ensure increased switching reliability for control and signal circuits.
• Another alternative to mechanical relays is the use of semiconductor relays. The CSS series from ComatReleco can reliably switch currents from as low as 1 mA (DC) and 35 mA (AC).

Free wheeling diodes protect against voltage spikes when the supply current of an inductive DC load is suddenly switched off. To this purpose the diodes are connected parallel to the inductive DC consumers, so that they are used by the supply voltage in theblocking direction. Afrer the supply current has been switched off the self-induction of the coil ensures that the current continues to flow in the original direction. Without a free wheeling diode, this would result in a voltage spike that adds to the operating voltage and could damage or destroy the switching path. However, with a free wheeling diode, the voltage spike is limited to the forward voltage of the diode (for silicon about 0.7 V). This protects the electronic components, but also the switching contacts, very effectively against voltage spikes.

Solid State Relays (SSRs) are particularly interesting when special requirements regarding environment, switching frequency or signal quality apply:

• Robust against mechanical stress: SSRs are resistant to vibration and shock.
• Frequent switching cycles / fast switching: Without mechanical contacts, SSRs are ideal for applications with many switching operations or high switching frequency.
• Rare switching operations: Even with very low switching frequency, SSRs remain reliable since no contact corrosion can occur.
• Very long service life: With no moving parts, SSRs hardly wear out and achieve a much longer lifetime than electromechanical relays.
• Low-noise or silent operation: They operate completely noiselessly and without contact sparks.
• Zero-cross switching in AC: Many SSRs switch at the zero-crossing of the AC voltage and thereby reduce voltage spikes, especially with inductive loads. Our CSS-Z* and R10-Z1Z* series feature zero-cross switching.

Note: At higher loads, SSRs generate heat. Depending on the application, suitable cooling or mounting on a heat sink is required.

There are two ways to retrofit an existing industrial relay with timing functions.
Time cubes are ideal when a socket and relay are already installed and only a single timing function needs to be added. The time cube is simply plugged between the socket and the relay and adjusted via DIP switch or potentiometer. It is available for industrial relay series C2 and C3, as well as for the Long Life series C2x and C3x.

Alternatively, time modules can be used. These modules are inserted into the socket’s module compartment and, compared to time cubes, offer more timing functions and longer setting ranges. They are available for sockets S3-M0, S3-M0R, S3-M1, S3-M1R, S5-M, and S5-MR and are compatible with industrial relays C3 and C5, as well as Long Life relays C3x.

Both solutions allow time relays to be configured with up to three changeover contacts – more than is usually possible with standard time relays.

The process is the same for almost all time relays. First, select a function using the potentiometer. Each letter (A, E, W, K, etc.) stands for a specific function, which is described on the side of the relay or on the package insert.

Next, select the time range, whereby the selected range always corresponds to the maximum value. The last potentiometer is then used to fine-tune the time setting. For example, if you want to set a 30-second switch-off delay, it would look like this:

Function: A

Time range: 60 seconds

Fine adjustment: On a scale of 0-6, the potentiometer is then set to 3 (6 = 60 seconds, 3 = 30 seconds, 1 = 10 seconds).

A latching relay is a bistable relay that retains its switching state even if the supply voltage is interrupted. This means that the last selected switching position - whether switched on or off - remains reliably stored until the relay is deliberately switched over.

A latching relay is used wherever the switching status must be retained after a power failure or interruption. This means that installations or systems can continue to operate safely and stably after an interruption without having to reset the status.

The most important advantages include high energy efficiency and operational reliability. Energy is only required during the changeover, but not to maintain the status. At the same time, the ability to maintain the switching state even in the event of a loss of voltage provides additional reliability and protection against unwanted changes in operation.

A remanence relay works through magnetic remanence: when the relay is switched, residual magnetism remains in the magnetic core, which keeps the armature in its position even if the supply voltage is switched off. The switching state is therefore stored stably until a new control signal generates an opposite magnetic field that compensates for the existing residual magnetism. Only then is the relay deliberately switched into the new state. In this way, it only requires energy during the switching process and combines high efficiency with operational reliability.

Latching (remanence) versions are available for our industrial relay series C3, C4, C5 and C9. In the product code, they are identified by the letter R in the 3rd position: C3-R*, C4-R*, C5-R*, C9-R*.

In the railway sector, we offer latching versions for the R3-R.

Voltage, current, frequency, active power, apparent power, cos Phi, Delta Phi (phase sequence)

The device data sheet and the package insert contain a description of the menu navigation, etc.

Press both arrow keys simultaneously to access the menu. When you enter the settings, you will be guided through the menu automatically.

To measure currents greater than 5A, current transformers are required that are specified for 5A on the secondary side. This allows high currents to be measured, but the scaling factor must then be adjusted in the settings.

This may be caused by a small residual voltage in the circuit, which is sufficient to prevent the relay coil from dropping out. It only needs 0.1*Un to remain energised! With a 230VAC coil, the relay would therefore only drop out at <23VAC!

Long wires/strands often cause induction voltage, which prevents the relay from dropping out. ComatReleco has developed the CEM01 interference suppressor for this purpose. This interference suppressor is connected in parallel to the coil and compensates for the residual current in the wires. This allows the relay to drop out cleanly.

If a relay or contactor comes into contact with fresh or dirty water, reliable operation is no longer guaranteed. Corrosion of contacts and conductors can occur, especially in combination with dirt or salts. Even if the component appears to work again after drying, there is still a risk of hidden damage.

A relay affected by moisture can fail unpredictably, get stuck in a switching position or transmit faulty signals. There is also a risk of internal short circuits or arcing, especially in high-current applications. Such failures not only jeopardise operational safety, but can also result in considerable consequential damage.

For this reason, it is always the better and safer decision to replace an affected relay or contactor. The costs for a new device are comparatively low, while the potential costs due to failures or consequential damage can exceed the acquisition costs many times over. This is the only way to ensure the usual quality and reliability in the long term.