Author: Abdullah Darcin

Signals, solenoid valves, power and load lines must be quickly controlled and monitored by intelligent relays that ensure signal transmission in accordance with IEC 61508 standard and SIL 3 rating. Compared to standard relays, intelligent safety relays provide reliable line and load monitoring, such as the GM International D5000 series modules.

Safety relays with line and load monitoring

From a functional safety perspective, safely deactivated relays can be used in process automation areas that require a functionally reliable shutdown according to SIL3 and IEC 61508 requirements. They securely manage offline, normally energized and secure states. For more information about TERMINATIOON BOARDS services, contact the numbers listed on the site.

In terms of “smart” operation, these models are equipped with auxiliary inputs/outputs and communication interface. They also allow diagnostics such as supply voltage configuration and load resistance check, internal coil integrity and ground fault. For more information about SURGE ARRESTERS services, contact the numbers listed on the site.

Why choose a smart relay?

Smart relays provide diagnostics to the system. Then, compared to standard relays, they extend the available voltage and current ranges. Finally, they support communication technology. GM International D5294S and D5295S relays support Modbus communication via RS485 cable. Up to 127 modules can be organized into a multi-link network and can be monitored and configured from a single master unit. For more information on SIL 2 services, contact the numbers listed on the site.

Each “slave” is uniquely identified by an address, making the value available for read/write operations when needed. The advantages of the Modbus protocol are obvious: a single communication interface for all connected relays; multipoint connection up to 1200 meters; no need for system digital inputs for alarm monitoring; information available on the actual fault type (while the alarm can only warn about the general fault status). For more information about SAFETY RELAYS services, contact the numbers listed on the site.

In some applications, the fault is reflected back to the PLC or DCS that drives the solenoid. The prerequisite is that the drive system can set an open circuit fault threshold on the output current of the digital output module. This is also called mirroring function. This reduces the need for an additional digital fault input to the system. For more information about SAFETY RELAYS services, contact the numbers listed on the site.

Typical practical applications of smart relays include normally energized solenoid valves, audible and visual alarms in Fire & Gas, high availability dual coil solenoid valves, single phase load break solenoid valves. The configuration of parameters that allow alarm activation depending on voltage, current and resistance is guaranteed via software. Coil integrity and drive condition can also be detected via software. Real-time monitoring and data logging capabilities are also available. For more information onMULTİPLEXER SYSTEMS services, contact the numbers listed on the site.

In the case of a normally energized solenoid valve, when the load current is at the rated value, the load is still energized. However, a fault was forced because redundancy was lost in the smart relay. In the case of a dual-coil solenoid valve, since each coil is sufficient to activate the valve, the two coils prevent false triggering when only one opens, thus increasing availability. In this context, the smart relay can detect the opening of a single valve coil. For more information about INTRINSICALLY SAFE ISOLATORS services, contact the numbers listed on the site.

In the case of an indicator for Fire & Gas applications, when the valve is affected by a partial short circuit of the solenoid coil, it can affect its ability to activate on demand. If the measured load resistance is below the acceptable value, an error is reported. These examples show that intelligent safety relays are the best system to provide real-time diagnostics and detect line and load anomalies in a completely transparent way. Would you like more information? Watch our webinar by clicking on the link below. For more information about ELCON ADAPTERS services, contact the numbers listed on the site.