Function:
32
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ANSI/IEEE C37.90-1978
UL file No. E58048
CSA file No. LR61158
Current Balance Relays are designed to sense un-
balanced current flow in a three phase system. The
primary application of Current Balance Relays is to
protect three phase motors against phase unbal-
ance or phase failure.
Operation:
With control voltage applied to the relay, the output
contacts will energize when the three phase currents
are balanced (including zero currents), and will be
de-energize by unbalance currents.
Current Balance Relays
PRODUCT SPECIFICATIONS
Sample Part No.
WCB-120AC-1-A
Type:
WCB = Current Balance
Control Voltage
(± 15%)
26 DC
48 DC
125 AC
120 AC
230 AC
380 AC
460 AC
Trip Adjustment Range
.5 = 0.1 amp to 0.5 amps
1 = 0.2 amp to 1 amp
2 = 0.4 amp to 2 amp
Options:
A = two normally open contacts
B = two normally closed contacts
PART NUMBER SELECTION
Notes:
1.
Remove black screw for access to the trip adjustment.
2.
Clockwise rotation of the adjustment potentiometer will raise the unbalance trip point.
3.
The output contacts are shown de-energized.
PART NUMBER SELECTION
Part Number
Line Current .....................................
Control Voltage ................................
Unbalanced Trip Point .....................
Drop-Out Time Delay .......................
Surge Withstand Capabiliy ..............
Operating Temperature ....................
Burden ..............................................
Contact Ratings ................................
WCB Series
Three Phase, AC current, 50-400 Hz Direct or from CT.
5 amp continuously
20 amp, 30 sec.
200 amp, 0.10 sec.
See Part Number Selection
Screwdriver adjustable.
Adjustment range in
accordance with ordering information. (The unbalanced
value is defined as the difference between the highest
and the lowest phase current).
0.9 to 1.3 seconds
In compliance with C37.90B ANSI/IEEE
-40oC to +70oC
Current input: 5.0 VA, Phase Control voltage: 3.0 VA
One set, N.O., One set N.C.
5 amp resistive at 120 VAC or 28 VDC
60 or 87
13
/64" DIA.
4 MTG. HOLES
4
1/
4
5.0
5
1/
2
3 1/2
4.0
5.0
TERMINAL STRIPS
#6 - 32 SCREWS
WILMAR Protective Relays – WCB Series
Note: Dimensions in inches. Multiply values by 25.4 for dimensions in mm.