| Failed
Heater - Fast Visual Indicator Single Phase Heater A cost effective approach for monitoring the operation or failure of a heater element is to use a Go/No Go current indicator like the LCS10T12 connected to an LPMG12. The current carrying wire is passed through the LCS10T12 toroidal sensor. The current sensor can be placed at any location along the wire, even hundreds of feet away from the monitored load. The wires on the LCS10T12 are connected to the LPMG12 LED indicator. These two components can be up to 500 feet apart. The LPMG12 is mounted in the control panel next to the heater’s temperature control (Fig. 2). The Go-Glow Indicator, along with the indicator light on the temperature control, displays four events for viewing by the operator. As long as both indicators glow simultaneously, the system is OK (as shown in Fig. 2). If only one glows, the system needs servicing. |
|
 |
| Three
Phase Heater
This same approach can be applied to three phase bank heaters. For three phase systems, a Go-Glow Indicator is installed for each phase of the three phase heater. As above, the three Go-Glow Indicators are mounted in the operator’s panel next to the temperature control. The operator watches the temperature control and three panel mounted Go-Glow Indicators. Operation: If all four indicators are ON, the system is OK. If all four are OFF, the system is OK. If the temperature control is ON and one of the Go-Glow Indicators is OFF, that heater or control relay has failed open. If any of the Go-Glow Indicators glow when the temperature control is OFF, a control relay has shorted. Note: If the system has a 3 wire (delta or wye) bank heater, a single shorted control relay cannot be detected. Two must fail short before this condition is displayed. |
 |
 |
 |
| Three
Phase Heater Unsupervised Equipment Active heater monitoring can be added to unsupervised machines and equipment. The figure below shows the connection for monitoring a 3 phase bank heater in an unsupervised piece of equipment. The TCS current interface switches are selected to monitor the current flowing to the heaters. When the current flowing exceeds 2 amps, the TCS’s solid state output is closed or opened depending on the model selected. The temperature controller can be an analog input in the PLC or a separate controller. In the diagram, the output of a separate temperature control and each of the three TCS’s are connected to four digital input modules of the PLC. Each time the temperature control energizes the solid state control relays, the PLC is notified through the temperature control input. The PLC then checks each of the inputs connected to the TCS’s to see if all heaters are operating. When the temperature control de-energizes the solid state control relays, the inputs are checked to see if the solid state control relays have turned OFF or have failed short. When appropriate, the PLC sends an alarm signal to the main control hub. The operator can evaluate the situation and schedule repairs. |
 |
 |
 |
||||||||||
 |
 |
 |
 |
 |
 |
 |
 |
 |
 |
 |
|
 |
|||||||||||
 |
 |
 |
 |
 |
 |
 |
 |
 |
 |
 |
 |
 |
 |
 |
 |
 |
 |
 |
 |
 |
 |
 |
