Introduction

The BFAS model #SS9602 is a newly patented battery monitor holding patent # 5744932.

Relying on the proven relationships between current and impedance, model#SS9602 detects battery failures, inverter shut down and transfers to bypass.

As a battery develops problems, it's impedance will rise and less A/C current will flow. AC current is a normal, though minor, component in the charging circuit of battery systems.

This monitoring instrument is adjusted to alarm at a low current threshold, allowing time for a pre-emptive battery service to replace the failed cell or battery before the system fails.

DC filter capacitors are monitored via a high current alarm set-point. As DC filter capacitors deteriorate, there is a rise in AC current. Model #SS9602 will sound an alarm that will prompt replacement of the DC filter capacitors before the system performance is compromised.

Without shutting down your system, installation is simple and non-invasive!

 

Theory of Operation

BFAS model #SS9602 is designed to monitor true on-line UPS
System batteries, i.e., the inverter is powering the load at all times when utility and/or battery power is available. It will sound an alarm if the batteries fail, the DC filter deteriorates or when the inverter stops.

An on-line UPS system reflects the AC ripple current found in the battery system. This ripple current remains relatively constant provided the battery impedance remains the same. If the battery impedance rises the ripple current lessens. This long overlooked phenomenon, which is the basis for the BFAS patent, tells more about a system's capability than any other product on the market today.

 

When impedance of the batteries goes up current goes down

When the DC filter impedance goes up current goes up

When the inverter stops current goes down

When load goes up current goes up

When load goes down current goes down

Note: Some significant load changes may require that the monitor be readjusted to allow for the changes.

 

Alarm Condition Evaluation Procedures

It is important that a record of the initial stop of the monitor and any changes to the set up be kept for future reference. Normal operating load should also be noted.

 

The following conditions can cause the monitor to go into alarm.

1. Failure of one or more batteries in the system. (low alarm, red low alarm LED goes out)

2. Failure of one or more DC filter capacitors. (high alarm, red high alarm LED goes out)

3. Significant load changes. Increased load = high alarm, (high alarm, red high alarm LED goes out), decrease load = low alarm. (low alarm, red low alarm LED goes out)

4. Unit transfers to bypass. (low alarm, red low alarm LED goes out)

5. Rectifier shut down due to failure or during normal operation of the system when recitifier shuts down during a utility outage. (low alarm, red low alarm LED goes out)

 

Alarm condition 1. (low alarm, red low alarm LED goes out)

A. Eliminate alarm condition 3,4, & 5 by checking UPS System.

B. Use Battery Evaluation Procedures on page 4 of this manual to isolate the defective batteries.

Alarm condition 2. (high alarm, red high alarm LED goes out)

A. Eliminate alarm condition 3 by checking UPS System.

B. Conduct a maintenance check of the DC filter capacitors.

Alarm condition 3. (low alarm, red low alarm LED goes out) (high alarm, red high alarm LED goes out)

A. Check for load changes. Readjust the monitor using installation procedures if the load changes are permanent.

Alarm condition 4. (low alarm, red low alarm LED goes out)

A. Resolve the UPS problem and restore UPS to normal mode.

Alarm condition 5. (low alarm, red low alarm LED goes out)

A. Rectifier shut down for utility failure: Wait for return to normal conditions.

B. Rectifier shut down for no apparent reason: Take action to protect your load. Batteries will be completely drained and the UPS will shut down. Restore UPS to normal operation.

Note: For any alarm condition: Turn armed switch to off, resolve the alarm and be certain to re-arm the monitor.

 

Better Evaluation Using "Current" Technology

(this test must be done with the UPS system operating under normal load conditions)

The following procedure was developed to help our customers troubleshoot their battery strings and to help them understand how our patented , AC current, battery monitor detects battery problems before power failures and/or load failures.

On an on-line UPS System, SCR or transistorized unit there should be an acceptable level of AC ripple current and voltage imposed upon the battery string.

Take an AC current reading on the battery string by positioning an AC "clamp on probe" around any battery cable in a single string or around all the positives or all the negatives in parallel strings.

Now take a reading on each individual string. If the batteries are capable of supplying DC current during a power failure, AC current will be present. If either or both readings show zero amps, that battery string/strings has a problem. The high amp string will be the better string.

You can isolate the problem simply by taking the following readings.

1. AC ripple voltage on the entire string. This will be a small number of AC volts, 1 VAC to as high as 2 VAC. Much higher than that indicates a problem. The problem may be in the UPS product, i.e., the DC filter capacitors are open or have high impedance. The total VAC will be evenly dropped along the battery string. This is OHms LAw (the sum of the voltage drops in a series circuit will equal the total voltage applied). Bad cells/jars will have higher millivolt drops than good cells/jars. High voltage drops equal high impedance which equals a bad cell/jar.

2. Determine and record AC millivolt drops on each cell/jar. Bad cells/jars will have as much as 100 times the millivolt drop found on the good cell/jar. Shut down system. Replace the defective cells/jars and you should see ripple current appear when the system is returned to normal operation. Identical strings should have similar currents and similar voltage drops if the UPS load currents are equal. Take your readings from connector to connector, not post to post. This will check the connections as well as the battery.

The AC ripple is directly related to the impedance of the battery. Impedance of the battery is directly related to the batteries ability to do work.

Once you use this procedure you will fully understand how, by constantly monitoring the AC ripple current with the BFAS model #SS9602, you can detect battery problems before load failures.

Our monitor has successfully detected battery failures, untorqued connections and DC filter failures. It will detect open fuses or open disconnects on the DC link. No other battery monitor can do as much, no matter how much you pay for it.

With our non-invasive single connection we don't add connection problems to your battery strings and we don't have any printer or software problems. We use Ohm's law. It's that simple.