Douglas Krantz - Technical Writer - Describing How It Works

No LEDs are Lit on the BPS but the SIGA-CT1 is Blinking

By Douglas Krantz | Maintenance

No LEDs are Lit on the BPS but the SIGA-CT1 is Blinking

No LEDs are Lit on the BPS but the SIGA-CT1 is Blinking

Greetings Douglas,

I have a supervisory issue on the EST panel for a BPS [Supplemental Notification Appliance Circuit {NAC} Power Suppl]. I have power coming into the BPS, but the green AC led is not lit. The SIGA-CT1 [Addressable Input Module} is also blinking red.

Thank You, CO

There are three issues that are being described.

EST SIGA-CT1 Fire Alarm System Input Module

The SIGA-CT1 is an input module for the building's fire alarm system. It is wired so it will look at, or monitor, the trouble contacts of the EST BPS (Booster Power Supply).

When something is not normal for the BPS, like a problem with one of the Notification Appliance Circuits (NACs), ground fault, battery trouble, internal problem with the BPS, or loss of power, a relay inside the BPS relaxes and closes contacts; the BPS's relay is sending a trouble signal.

The SIGA-CT1 senses the trouble signal, and sends that trouble signal to the control panel as a supervisory trouble. The SIGA-CT1 has its own way of saying that something is not normal; the control panel receives a trouble (not a supervisory) to indicate that the SIGA-CT1 is not normal.

In other words, it is doing its job.

EST BPS Power Supply

The BPS Power Supply is there to power some of the horns and strobes, and it has several indicator lights to show its status. A green light turned on, and no other light means that everything about the power supply is in the normal, working condition.

If no other light is lit on the power supply, the BPS power supply is saying that the battery tests OK, the circuits powered by the BPS aren't ground faulted, and all four NAC power circuits are normal.

The green power-on light says that AC power is applied, and also that there isn't any internal problem with the power supply.

AC Power

AC power is provided to the BPS power supply at the AC power input. However, a turned-off Green Power-On LED is kinda dumb; if it is off, it doesn't show why there is a problem, only that there is a problem. The problem could be on a different circuit breaker somewhere else in the building, or the problem could be inside the BPS.

This is a time sensitive issue. When the AC Power LED is not lit, the BPS is running on the battery backup. The size of the backup batteries has been designed to keep the system working for at least 24 hours, and at the end of the 24 hours, be able to sound the alarms for 5 minutes.

The BPS will probably last longer than 24 hours from the time the green light turned off, but I wouldn't count on that.

Call your fire alarm service company. They are familiar with this kind of problem, and can help.

Douglas Krantz


Yeah, the green AC light is off and the batteries are dead. I put a set of new batteries to see if that was the problem and 2 days later when I went to check, they were dead again and the problem re-occurred.

I have two panels side by side. One has the NAC circuits and the other has the initiation devices. The one with the NACs is the one with the problem, the other one is working fine. Would that still be a problem coming from another circuit?

I have called the fire alarm company to come and take a look. Your info has helped my knowledge and thank you very much.

Thank You, CO

The red NAC power supply on the wall has two sources of power: the primary power source is the utility power, and the secondary power source is the batteries.

There are separate LEDs for the two separate power sources: the green "Power-On" LED shows the status of the primary power, and a yellow "Battery Trouble" LED shows the status of the secondary power.

Actually, the green power-on LED isn't truly a "Utility Power On" LED, the green power-on LED is an internal power supply (on the circuit board inside of the red box on the wall) power-on LED.

Primary Power Status LED

That green power-on LED is showing the overall status of the primary power for the red box on the wall.
  • If the utility power is off, then the internal power supply is also off. That means the primary power is off, and the green power-on LED is turned off.

  • Even if the utility power is on, but something is wrong with the internal power supply so the internal power supply isn't working. That still means the primary power is off, and the green power-on LED is still turned off.

Secondary Power Status LED

The yellow "battery trouble" LED is showing the status of the secondary power for the red box on the wall: the batteries. If the NAC power supply determines the batteries won't hold a charge, the battery trouble LED will be on; if the batteries are dead, or disconnected, the battery trouble LED will be on.

Catastrophic Failure

LEDs, though, require power to be lit. If the NAC power supply's primary power supply isn't working, and the NAC power supply's secondary power supply (the batteries) isn't working, none of the LEDs on the power supply can get power to turn on. In other words, if there is a catastrophic failure of the NAC power supply, none of the LEDs will be lit . . . at all.

Independent Panels

The NAC power supply (the red box on the wall) is always using electricity. Normally, the batteries are also being charged by the internal primary power supply on the circuit board. If the internal power supply isn't working (the green power-on LED is off), the secondary power supply (the batteries) is the only source of electricity, and the batteries are slowly being drained.

As far as AC power goes, the two panels next to each other are independent panels. One can be working just fine while the other one isn't working. In other words, they don't affect each other.

Douglas Krantz
Life Safety
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