Frequently Asked Questions
Guaranteed solutions for electrical contractors tasked with designing and installing complicated lighting and emergency off circuits for Siemens medical imaging equipment.
General Faq's
SIEMENS has updated the lighting control circuits and has specified that a 24VDC power supply now must be used for the control voltage that is going into the SIEMENS System Cabinet for controlling the XRAY warning lights and Exam room lights. This is different from the past, which was specified to be 24 VAC. The reason is that SIEMENS only wants DC voltage going into the switching circuit to eliminate the possibility of electromagnetic interference being induced into the SIEMENS equipment by the lighting circuit. However, when using DC voltage to control a relay coil, when the relay coil voltage is removed, the DC relay coil can produce a momentary high voltage spike that can damage sensitive electronics. For this reason, SIEMENS specified a freewheeling diode be installed on all DC relays being used in the lighting circuit. A freewheeling diode will immediately short out the momentary high voltage spike and protect the circuits. The XRAY LIGHTING LCBEX277-2 Lighting Control Box has the diodes installed and factory tested, so you can be sure you are meeting all of SIEMENS specifications.
Simply stated, because the EPO button must perform multiple duties when depressed. When activated, the EPO circuit must:
- Send the SHUNT TRIP VOLTAGE to the MAIN CIRCUIT BREAKER and cause it to trip.
- Send a signal to the UPS systems to shut off
- Not reset automatically, but be manually reset
- Be protected against accidental activation
The XRAY LIGHTING EPO station provides all of the above functions and more. Most installations will require at least two sets of contacts and two separate circuits on each button station