PCS100 UPS-I
User Manual
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Additionally to Transient detector optimization, the PCS100 UPS-I incorporates a source impedance voltage drop
compensation which ameliorates harmonic voltage disturbance at the point of coupling which is commonly
caused by the connected load causing voltage drops across the supply impedance.
There is always a requirement for some delay in detecting a voltage event and filtering due to reject noise typical
of most power systems. The default parameters have been chosen carefully to balance the need for rapid
response to real events against the desire to reject nuisance disturbances.
The response of this detection is set by parameter
532 Transient Threshold
with the supply voltage set point
parameter
121 Utility Voltage
.
When the Transient detection has been triggered the PCS100 UPS-I will display "222 Discharge Transient" in the
event log.
9.1.3
Frequency detection
Frequency detection is based on the deviation of the Supply frequency from the supply frequency set point.
The threshold for this detection is set by parameter
533 Frequency Threshold
with the supply voltage set
frequency parameter
122 Utility Frequency
.
When the frequency detection is triggered the PCS100 UPS-
I will display “Discharge Frequency” in the event log
.
Frequency detection typically is only used on supplies where the frequency can vary widely. The default threshold
setting is such that the detection will not be triggered when connected to a grid.
9.2
Transfer Description
As a single conversion type UPS the PCS100 UPS-I will transfer the load from the utility supply to the backup
energy storage if it detects a deviation of the supply voltage from the nominal value by more than that set by the
PCS100 UPS-I set points.
The PCS100 UPS-I is classified as VFD SX 211 for rated powers below 450 kVA and VFD SS 211 for rated powers
above 450 kVA according to IEC 62040-3.
According to this classification, the PCS100 UPS-I complies with Classification 2 (
2
11) performance for change of
operating mode from utility supply mode to energy storage mode.
The transfer from utility supply mode to energy storage mode is done by closing the Utility Disconnect which
consists of a naturally commutated SCR based electronic switch.
A SCR (thyristor) is a naturally commutated device that turns off at the next zero crossing, which could be as long
as 10 milliseconds later, and this presents problem when the need arises to immediately transfer the load at any
point in the cycle, i.e. to achieve transfer performance according to IEC 62040-3 Classification 2.
When turning off the Utility Disconnect, the PCS100 UPS-I utilizes revolutionary PCS100 Inverter commutation
capability techniques to force the current in the Utility Disconnect and turn SCRs off with typical transfer time of
1.8 milliseconds, resulting the minimum load voltage disturbance.
Without PCS100 Inverter commutation the Utility Disconnect SCRs would continue to conduct until the current
naturally decays in next zero crossing which may take up to ½ of a cycle.
When a transfer is performed the PCS100 UPS-
I status line will change from “On Line” to Discharging”
When the supply returns within these limits a “transfer back” sequence is initiated. First the PCS100 UPS
-I will
wait a short time to trust the supply is stable. Then it will resynchronize with the mains supply. Finally it will
switch on the Utility Disconnect and transfer back to the utility supply. If during this time the Energy Storage is
depleted it will transfer back regardless.
The following image shows a typical waveform of the PCS100 UPS-I output voltage during transfer from utility
supply to energy storage mode.