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ELECTRICAL INSTALLATION
Wire Size
Phase Sequence and Transformer Polarity
CAUTION:
CAUTION:
2–16
AC Inputs - 4 X 1/5A CT, 4 VT
Terminal
10
11
12
13
14
15
16
Use the following guideline when selecting wires or lugs to connect to terminal strips A, B,
C, D, E, F, G, H, and terminal blocks J, K. Note that the first two bullets are applicable to
terminal blocks J and K only:
•
12 AWG to 22 AWG (3.3 mm
mm (0.375") maximum diameter ring terminals.
•
14 AWG to 22 AWG (2.1 mm
(0.375") maximum diameter ring terminals. Two ring terminals maximum per circuit.
•
Suggested wiring screw tightening torques are: terminal strips A-H tighten to 4.5 in-lbs
(0.5 N-m) and terminal blocks J, K to 15 in-lb (1.7 N-m).
Figure 2-18: Fiber Connector Types (S - ST)
For correct operation of the relay features, follow the instrument transformer polarities,
shown in the Typical Wiring Diagram above. Note the solid square markings that are
shown with all instrument transformer connections. When the connections adhere to the
drawing, the arrow shows the direction of power flow for positive watts and the positive
direction of vars. The phase sequence is user programmable for either ABC or ACB rotation.
The 845 relay has four (4) current inputs in each J slot and K slot. Three of them are used
for connecting to the phase CT phases A, B, and C. The fourth input is a ground input that
can be connected to either a ground CT placed on the neutral from a Wye connected
transformer winding, or to a "donut" type CT measuring the zero sequence current from a
grounded system. The relay CTs are placed in a packet mounted to the chassis of the
845 relay. There are no internal ground connections on the current inputs. Current
transformers with 1 to 12000 A primaries may be used.
Verify that the relay's nominal input current of 1 A or 5 A matches the secondary rating
of the connected CTs. Unmatched CTs may result in equipment damage or inadequate
protection.
IMPORTANT: The phase and ground current inputs correctly measure up to 46 times the
current input's nominal rating. Time overcurrent curves become horizontal lines for
currents above 20 × PKP.
Description
VT1_RETURN
VT2_IN
VT2_RETURN
VT3_IN
VT3_RETURN
VT4_IN
VT4_RETURN
2
2
to 0.3 mm
): Single wire termination with/without 9.53
2
2
to 0.3 mm
): Multiple wire termination with 9.53 mm
845 TRANSFORMER PROTECTION SYSTEM – INSTRUCTION MANUAL
CHAPTER 2: INSTALLATION
- Quick Links:
- 845 Order Codes
- Protection
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