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Power Surge Condition, PST-600-48: The surge rating is 1000W or 8.33A (1000W ÷ 120VAC
= 8.33A). When the instantaneous value of the AC output current tries to exceed the
above value of 8.33A, output current limiting is initiated that clamps the peak instantane-
ous value of output current at 8.33A. Output current limiting results in drop in the peak
portion of the AC output voltage waveform and hence, the RMS voltage also drops. The
extent of voltage drop is proportional to the rated surge current of the load minus 8.33A.
Hence, higher surge current of the load will produce higher voltage drop. For example,
considering Resistive Load with Power Factor =1 (voltage and current are in phase), cur-
rent limiting will occur near the peak portion of the voltage waveform during every half
cycle (half cycle lasts for 8.33 msec at 60Hz). 1000W is the value of surge power averaged
over 1 to 2 msec during every half cycle of 8.33msec. If this situation continues for 2 to 2.5
sec, overload condition is activated and the AC output is shut down
Power Surge Condition, PST-1500-48: The surge rating is 3000W or 25A (3000W ÷ 120VAC
= 25A). When the instantaneous value of the AC output current tries to exceed the above
value of 25A, output current limiting is initiated that clamps the peak instantaneous value
of output current at 25A. Output current limiting results in drop in the peak portion of
the AC output voltage waveform and hence, the RMS voltage also drops. The extent of
voltage drop is proportional to the rated surge current of the load minus 25A. Hence,
higher surge current of the load will produce higher voltage drop. For example, con-
sidering Resistive Load with Power Factor =1 (voltage and current are in phase), current
limiting will occur near the peak portion of the voltage waveform during every half cycle
(half cycle lasts for 8.33 msec at 60Hz). 3000W is the value of surge power averaged over
1 to 2 msec during every half cycle of 8.33msec. If this situation continues for 2 to 2.5 sec,
overload condition is activated and the AC output is shut down.
Overload Condition: If there is a continuous overload of 110% to 115% for 2 to 2.5 sec,
the output voltage will be shut down. Red LED marked “OVERLOAD” (3 in Fig 6.1 for
PST-1500-48 and 3 in Fig 6.2 for PST-600-48) will turn ON, the Green indication light on the
GFCI outlet will be OFF and buzzer alarm will sound. The Green LED marked “POWER” /
"POWER ON" (2 in Fig 6.1 for PST-1500-48 and 2 in Fig 6.2 for PST-600-48) will continue to
be lighted. The unit will be latched in this shut down condition and will require manual
reset. To reset, switch OFF the unit using the ON/OFF Switch (1 in Fig 6.1 for PST-1500-48
and 1 in Fig 6.2 for PST-600-48), wait for 3 minutes and then switch ON the unit again.
Before switching ON, determine and remove the cause of overloading.
Short Circuit Condition: Short circuit condition will be detected when the AC output
voltage drops to 80VAC or lower over a period of around 1 to 1.5 sec. The AC output
voltage will be shut down thereafter.
Red LED marked “OVERLOAD” (3 in Fig 6.1 for PST-1500-48 and 3 in Fig 6.2 for PST-600-
48) will turn ON, the Green indication light on the GFCI outlet will be OFF and buzzer
alarm will sound. The Green LED marked “POWER” / "POWER ON" (2 in Fig 6.1 for
PST-1500-48 and 2 in Fig 6.2 for PST-600-48) will continue to be lighted. The unit will
be latched in this shut down condition and will require manual reset. To reset, switch
OFF the unit using the ON/OFF Switch (1 in Fig 6.1 for PST-1500-48 and 1 in Fig 6.2 for
PST-600-48), wait for 3 minutes and then switch ON the unit again. Before switching ON,
determine and remove the cause of short circuit.
SECTION 10 |
Protections
Summary of Contents for PST-1500-48
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