Level limiter HW-S SMHC2
with safety function
Application and function
In conjunction with the appropriate IGEMA level probes, the level limiter (HW-S) SMHC2 is a self-monitoring limiter with safety function in accordance with the Pressure Equipment Directive (PED).
The product meets EU Directive 2014/68/EU (PED). Conformity (CE marking) is certified in accordance with Annex III, Modules B+D (Category IV); notified body NB 0035.
Regulations applied:
AD2000, EN12952-11, EN12953-9, EN61508-1/-2/-3, EN61326-1, EN61010-1
Due to the permanent self-monitoring, the limiter ensures the safety function. Thus it can be implemented in systems with safety requirements up to SIL 3.
Function SMHC2
The SMHC2 (HW-S) level limiter works in conjunction with the IGEMA level probes on the basis of the conductive fill level method of measurement whereby the electric conductivity of the liquid is used. The conductivity of the medium is measured in µS/cm. For the secure functioning of this method of measurement a minimum conductivity of the substance to be measured is required.
The conductive method of measurement shows two results: electrode submerged or electrode uncovered or switch point reached or not reached. Before installation the electrode must be adjusted to the length at which the switching procedure is to be executed, e.g. for switching off burner and interrupting the safety circuit.
LEDs in different colors show the state of the system. This assists the troubleshooting.
If all conditions for correct operation are met, the safety circuit for the steam generator is enabled (burner can switch on).
The current across the electrical contacts of the safety circuit is limited by a 4A fuse. Thus jamming of the contacts is avoided.
In the case of a high liquid level, the output (relay) of the safety circuit is deactivated after a total adjustable delay of 4s, 8s, 12s or 16s, thus the burner is cut-off. The preset delay time is 4s.
A latching is not implemented into the SMHC2. It has to be installed by the operator.
The permanent self-monitoring ensures the functionality, thus a test button is not necessary.
Probes
| Probe | PS | TS | Connection | Electrode length |
| EL040 | PS: 32bar | TS: 239°C | G ½“ | 125mm – 1700mm |
| EL40-B | PS: 32bar | TS: 239°C | G 3/4“ | 125mm – 1700mm |
| EL240 | PS: 200bar | TS: 367°C | G ½“ | 150mm – 1700mm |
Technical basic equipment
- SMHC2 is delivered in a plastic plug-in housing for installation in control panels
- Fixation on standard rail 35 mm according to DIN EN 50022 or directly screwed to chassis plate
Images
