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Monitoring devices perform a wide range of functions for the protection of people and machines.
The GSM alarm module (GSM = Global System for Mobile Communications) enables cost-effective remote control of industrial and private building management, e.g. of heating, air-conditioning and cooling systems. But it is also possible to safely control elevators and escalators and all kinds of production equipment, such as machines, automatic devices and conveyor belts. The GSM alarm module is particularly suitable for monitoring remote plants, i.e. for monitoring the heating of summer houses or the pumps of a water treatment plant.
Using voltage relays, current relays, fuse monitors, miniature circuit breakers, residual current operated circuit breakers or surge arresters fitted with auxiliary switches or signal contacts, there are virtually no limits to the type of monitoring tasks that can be carried out. The use of remote controlled mechanisms with miniature circuit breakers and residual current operated circuit breakers also allows realization of a range of cost-effective and interesting solutions.
Because the availability of mobile networks cannot be guaranteed, GSM alarm modules should not be used for safety-relevant control functions.
Fault signaling units are used in small plants where the installation of complex fault signaling systems would be too cost and laborintensive. In the event of a fault, they enable fast fault localization of all monitoring devices and limit monitors from a central location. This increases plant availability. With the correct sensor configuration, they also provide the option of preventative maintenance.
EMERGENCY-STOP circuits are common safety measures in all laboratory equipment and industrial plants. The EMERGENCY-STOP modules used here must meet the most rigorous demands with regard to functional reliability. Benchmark is the degree of selfmonitoring. The Machine Directive 98/37/EC, valid from 31.2.1994, only specifies global safety standards. Details on how to implement individual safety demands are defined in standards, e.g. by the European Committee for Electrotechnical Standardization (CENELEC), which form the basis for international standards.
Level relays are used for the monitoring and control of conductive, non-combustible liquids and powders. They ensure overflow and dry run protection. Due to their sensor performance, the devices can also be used for general resistance monitoring.
- Green LED: lights up when operational voltage is applied
- Yellow LED: lights up if MIN output relay is activated
- Red LED: lights up if MAX output relay is activated.
The measuring range up to 450 kΩ enables a differentiation between foam and liquid. It also increases the universal application for resistance measurements.
Due to its low-frequency, electrically isolated measuring circuit, the device has a high immunity to interference against system coupling, which enables cable lengths of up to 1500 m and suppresses the effects of electrolysis in the liquid.
Line circuit relays are used to interrupt circuits and prevent electromagnetic fields in circuits where there are currently no active loads. If the loads are disconnected, and the line circuit relay measures a usage of only 2 to 20 VA – adjustable – it disconnects the cable to the supply voltage and switches over to extra-low voltage. As soon as loads are reconnected, the line circuit relay detects the increase in usage and switches back to the supply voltage. While the line circuit relay switches off any unnecessary system components, it is not a device for ensuring isolation in the sense of safe disconnection.
The line circuit relay is unable to detect consumers with electronic power supply units, e.g. electronically controlled vacuum cleaners. It is expedient to connect such equipment to a base load resistor (PTC resistor) so that the line circuit relay is reset to supply voltage.
Dusk switches are used for the demand-oriented switching of lighting installations for shop windows or paths in order to cut operating costs. A light sensor measures the level of daylight. Switching depends on the desired brightness. A time delay and the switching hysteresis prevent clock-pulse behavior. The sensor must be mounted so that it is not influenced by the lighting feedback.
The temperature controllers are used for controlling or limiting temperatures in residential and non-residential buildings, as well as in industrial areas. They're used for heating registers, panel and hot air heating and direct floor heating, as a limiting thermostat for air-conditioning systems and cooling systems, control cabinet cooling, etc. as well as for temperature control in humid and dusty rooms. Can also be used for inaccessible room temperature setting for rooms in public buildings, such as schools, dayrooms and comparable applications.
The p.f. controllers monitor the phase displacement between current and voltage. Because the phase displacement angle changes with the load of the motor, this measurement method is ideal for the monitoring of asynchronous motors for underload and no-load operation, independent of size. However, in some cases, the p.f. barely changes if the load of the motor changes, e.g. in the case of relatively minor load changes on large-scale motors or single-phase split-pole motors or collector motors.
The p.f. controller monitors single and three-phase asynchronous motors up to approx. 5 A (without current transformer) for underload and no-load operation. This is phase-sequence independent and increases plant availability. Typical applications are fan monitoring in the case of V-belt breakage, pump monitoring in the event of valve closure or dry runs. A current transformer is used for higher rated currents.
If the p.f. value set at the p.f. controller is fallen below for the duration of the set response delay, the output relay switches to the alarm state and the red LED lights up. If it exceeds the p.f. value, the output relay switches back without any significant delay.
The ultra compact p.f. controller requires only the smallest of spaces and saves costs.
Thermistor motor protection relays monitor the thermistors wound in motors. This helps prevent thermal motor overloads, e.g. due to high switching frequency, single-phasing, disabled cooling or excessive ambient temperatures. Up to 6 thermistors in series can be monitored. A conductor break in the sensor conductor will immediately trip the device. The device can also be used for monitoring wound quick-break switches – e.g. bimetal thermostats. This offers all-round motor protection.