Necessity and suggestion of UPS battery maintenanceWith the demand of the market,UPS has been widely used in various industries, and batteries have become the power guarantee of uninterrupted power supply system. UPS without batteries can only be called stable voltage and stable frequency power supply. When the power supply is abnormal, the battery changes chemical energy into electric energy, which is transferred to the load through the inverter in UPS into ac electric energy, so as to ensure the continuous operation of the load without interruption.
Valve-controlled maintenance-free sealed lead-acid batteries have been widely used in large, medium and small UPS, accounting for 1/4 ~ 1/2 of the total cost of UPS. According to the investigation, the life of the normal use battery is generally around 5 years, and about 50% of UPS faults are related to the battery at the end of use. Battery failure mainly for individual cells exist behind or float charging down, for time is short (capacity), need to start UPS battery when mains abnormal does not start loading, etc. It is necessary to make reasonable maintenance plan for the normal operation of UPS system, especially for the condition of battery.
Monitoring of battery floating charge pressure
(1) the monitoring device is usually equipped with a monitoring device in the medium and large UPS. The upper and lower limits of floating charge pressure are set through monitoring to monitor the health status of the battery at any time and handle any abnormality timely.
(2) use a multimeter to measure the floating charge pressure of the battery.
Through the above method, reference to YD/T799-2002 standard for communication valve control type sealed lead acid battery, battery charge, in a floating state down pressure deviation is not more than 480 mv (12 v battery), such as testing voltage deviation is big, you need to consider to carries on the observation and test again after filling pattern, such as into a floating after there is still no change, you will need to consider the following methods for testing verification.
Battery capacity test
In general, the following capacity test methods can be chosen for periodic capacity test of the battery.
2.1 off-line measurement (where conditions permit)
(1) the battery after a full charge from UPS let stand for 1 h, the environment temperature is 25 ℃ + / - 5 ℃ under the condition of external (smart) dummy load way, with 10 hours discharge rate discharge test.
(2) the terminal voltage, ambient temperature and time of the battery should be measured before discharging.
(3) during the discharge, the terminal voltage, discharge current and indoor temperature of the battery shall be measured and recorded, with a measurement interval of 1h. The discharge current fluctuation shall not exceed 1% of the specified value.
(4) the terminal voltage and room temperature of the battery shall be measured and recorded during the discharge, and the measurement interval shall be 1h. At the end of the discharge should be measured at any time in order to accurately determine the time to reach the discharge termination voltage.
(5) the discharge current multiplied by the discharge time is the capacity of the battery group. In 10 hours of battery discharge, if the temperature is 25 ℃, the actual measuring the capacity of the period shall be in accordance with the type conversion into 25 ℃ when the capacity of the Ce:
Ce = Cr/(1 + K (t - 25 ℃)] (1)
Where :t -- ambient temperature during discharge
K - temperature coefficient (10 hours discharge rate, K = 0.006 / ℃;
3 hours discharge rate, K = 0.008 / ℃; 1 hour rate is discharging, K = 0.01 / ℃)
(6) after the discharge, the battery group shall be charged, and the charge shall be more than 1.2 times of the released charge.
2.2 on-line measurement
(1) in the dc power supply system, adjust output voltage to the voltage protection, UPS power supply by the battery to the actual load, find out the lowest voltage of the battery in the discharge capacity, capacity of a storage battery as a test object with the worst.
(2) turn on the UPS to charge the battery pack, and stabilize the battery pack for more than 1h after it is fully charged.
(3) conduct a 10-hour rate discharge test for the battery with the worst discharge in (1). The terminal voltage, temperature, discharge time and room temperature of the battery should be measured and recorded before and after discharge. After every 1h measurement record, the discharge should be measured and recorded at any time when the discharge is fast enough to terminate the voltage, so as to accurately record the discharge time.
(4) the discharge current multiplied by the discharge time is the capacity of the battery group. If the room temperature is 25 ℃, should be in accordance with the type (1) the conversion capacity of 25 ℃.
(5) after the completion of the discharge test, the battery shall be recharged with a charger to restore its capacity.
(6) draw discharge curve according to measurement record data.
2.3 check discharge test method
In order to master the approximate capacity of the battery pack at any time, it is necessary to carry out the check discharge test. The method is:
(1) in the dc power supply system, the output voltage of UPS is adjusted to the protection voltage, which is powered by the battery to the actual load. The voltage, temperature, room temperature and discharge time of each battery shall be measured and recorded before and after discharging. Up to 30% ~ 40% of rated capacity.
(2) after the discharge, the battery shall be charged, and the charge shall be more than 1.2 times of the released charge.