S&C BankGuard PLUS, Руководство по установке

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12
S&C Instruction Sheet 1011-510
Grounded Wye Banks
Ç
WARNING
Do not enable communications by connecting radios, fiber optic cables, or dedicated
phone lines until this is called out in the instructions.
Before attempting to access an existing installation, check carefully for visible
or audible signs of electrical or physical malfunction (do this before touching or
operating the BankGuard Plus Control or any other part of the installation). These
warning signs include such things as smoke, fire, open fuses, crackling noises, loud
buzzing, etc. If a malfunction is suspected, treat all components of the installation,
including the control and associated mounting hardware, as if they were elevated
to primary (HIGH) voltage.
You must follow the sequence of installation steps outlined in this instruction sheet
to insure a safe and successful BankGuard Plus Control installation.
Step 2
Make the connections to the terminal strips on the back of the control.
The BankGuard Plus Control includes numbered terminal strips on the back of the
enclosure for external control-wiring connections. See Figure 1, Table 1, and the
electrical diagrams at the end of this instruction sheet.
Using the terminal strip illustrations, make the following connections:
A. The station ground to TB2-1.
B. The output terminals of three S&C 30-Volt-Ampere Potential Devices to TB1-9,
TB1-10, TB2-11, and TB2-12 (phase voltage return). The potential devices should
have a system voltage rating at least equal to the voltage appearing between the
intermediate tap points and ground, multiplied by

3.
C. The opening circuit of the bank switch operator, to TB2-4 and TB2-5.
D. The closing circuit of the bank switch operator, to TB2-2 and TB2-3.
E. The control device power source (48-250 Vdc, 100-240 Vac, 50 or 60 Hz, as
appropriate), to TB2-9 and TB2-10. Observe polarity if dc.
F. The “b” contact of the auxiliary switch on the bank switch operator to TB2-6.
Terminal TB2-10 may be used as the source for the wetting voltage. Set this
contact to open near the fully-closed position of the capacitor bank switching
device.
G. The space heater source, where applicable (120 Vac/60 Hz or 240 Vac/60 Hz).
H. Alarm circuit (optional) to terminals TB1-2 and TB1-3 for normally closed alarm
contacts. Use terminals TB1-4 and TB1-5 for normally open contacts.
I. If unbalance compensation is required, connect the output of a 30-Volt-Ampere
Potential Device to TB1-11 (Star voltage) and TB2-12 (Star voltage return).
Step 3
Check the circuits connecting the potential devices to the control device.
The circuits connecting the potential devices to the BankGuard Plus control must
be free of variable loads, variable voltage drops, and ground loops. This insures that
the monitored voltages accurately represent the magnitude and phase angle of the
bus voltages. Some possible errors affecting unbalance compensation are:
• Unbalanced or variable loading of the potential devices. (Note that this means
that station service transformers are not suitable.)
• Control-wiring voltage drops between the potential devices and the control.
To minimize voltage drops, connect the potential devices and the control with
dedicated circuits that are adequately sized.
• Example— A 1 amp current flowing through 1000 feet of #10 AWG wire results
in a 1 V drop in the voltage signal. This may be enough to affect the performance
of the protection scheme.