Burnham K50 manual Safety Switch Circuit

This thermocouple will cool in 45 to 90 seconds allowing the pilot line safety valve to close. This shuts off the flow of gas to the pilot. It is in this manner that 100% shut-off is achieved. If the operating control calls for heat during this period and the “Power On” switch is still in the “ON” position this relay will automatically sense the absence of pilot flame and the “Pilot Failure Alarm Lamp” will be activated as described in paragraph

(a)above.

d.SHUTDOWN INSTRUCTIONS

(1)Turn off all switches on panel(s).

(2)Turn off manual main and pilot shut-off valves.

10.EOP CONTROL SYSTEM – 5015B thru 5026B

The 5015B thru 5026B boilers utilize two EOP Control

Systems that are interconnected electrically thru all operating and safety controls. Should any of the aforementioned controls break the power supply circuit, both EOP Control Systems would be de-energized. The succeeding paragraphs describe the function and operation of each EOP Control System. Should a pilot failure on one EOP Control System occur, the other EOP Control System would not be affected. Thus main burners on the unaffected side would ignite on a “call for heat” and would continue to operate until the operating control was satisfied.

The EOP Control System functionally is the same as the EO Control System. The RA890F Protectorelay, however, is installed in a prewired control cabinet along with a terminal strip, “main power” switch, “main gas valves” switch, “main power” lamp, “main gas valves” lamp and “pilot failure” lamp.

The RA890F Protectorelay Primary Control is a non- programming amplifying relay which, when used with the Q179D Rectification Pilot (standing or continuous burning pilot) provides solid state electronic Flame Safeguard Protection during a “call for heat” pilot failure. Should this occur, main burners will shut down within 0.8 second, “Main Gas Valves Lamp” will go off, the Protectorelay will lockout on safety shutdown within 15 seconds and the “Pilot Failure Alarm Lamp” will be lighted. The thermocouple in the Q179D pilot will cool and, within 45 to 90 seconds, will cause

the L62GB-3C Pilot Safety Switch to which it in connected, to break the electrical circuit to the main gas valves as well as shutting off the flow of gas to the pilot. Thus 100% shut-off is achieved.

On the next call for heat the Protectorelay will immediately sense the absence of pilot flame and the

“Pilot Failure Alarm Lamp” will be lighted.

a.LIGHTING INSTRUCTIONS

(1)Turn off all switches on both panels.

(2)Turn off all manual main and pilot gas valves.

Wait at least five (5) minutes before proceeding.

(3)Push safety switch reset button on both panels.

(4)Turn on one pilot gas valve. Depress button on

L62GB-3C Pilot Safety Switch to which it is connected and light pilot with match. Continue to hold button in for one minute or until pilot remains lighted after button is released. Light second pilot using same procedure.

(5)Set operating control to desired temperature or pressure.

(6)Turn on Main Power Switch. Main Power

Lamps will light.

(7)Turn on Manual Main Gas Valves.

(8)Turn on Main Gas Valve Switch on both panels to light burners. Main Gas Valve Light on each panel will light.

Proceed To Paragraph 15- Minimum Input Adjustments (for diaphragm “Lo-Hi-Lo” or

motorized type gas valves)

SEQUENCE OF OPERATION EOP – See Fig. 52

b.NORMAL OPERATION – 5015B thru 5026B

(1)When the operating control calls for heat, terminal, #6 terminal of each RA890F Protectorelay is energized through terminals 1, 6

& 7 of their respective panel terminal strip.

(2)A component self-check circuit in each RA890F relay is activated which checks the electronic network of the relay.

(3)Flame rod circuit of each RA890F relay and its Q179D pilot proves the presence of pilot flame electronically.

(4)Terminal #5 on each RA890F is energized, and providing the “Main Gas Valve Switch” is “ON” (circuit closed), supplies power to its respective main gas valves.

(5)“Main Gas Valve” lamps will be lighted, main gas valves will open and main burners will be ignited by the pilot flames.

(6)When operating control is satisfied, terminals #6 and #5 on the RA890F relays are de-energized, main gas valves close and main burners are extinguished. “Main Gas Valve” lamps will go off.

(7)The Q179D pilots continue to burn.

c.SAFETY SHUTDOWN

(1) SAFETY SWITCH CIRCUIT

If limit control, Low Water Cut-off, operating control or any other electrical safety switch in the limit circuit opens, power to terminal #1 on both panels is interrupted, de-energizing both control panels causing all main gas valves on both sides to close and main gas burners are immediately extinguished. Both pilots will continue to burn. Normal operation can be resumed when the cause of the safety switch action is corrected. Make sure all manual resets are activated where involved.

63