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GEK-106621
4 HARDWARE DESCRIPTION
GEK-106621 4 HARDWARE DESCRIPTION
4.1 CASE
The DIAC relay consists of a case, cover, support structure, and a connection plug to make up the electrical
connection. The case is shown in Figure 6–5: DIAC 66K FRONT AND REAR VIEWS on page 6–9. The exter-
nal connections are shown in Figure 5–3: TYPICAL EXTERNAL CONNNECTIONS FOR MOTOR PROTEC-
TION on page 5–4. It has 10 connection points and a CT shorting bar. As the connection plug is withdrawn, the
trip circuit is broken prior to the current shorting bar engagement.
4.2 ADJUSTMENTS: DIGITAL UNITS
All customer settings for the TOC Alarm and TOC/IOC are accessible from the front of the relay. The relay
cover must be removed to gain access to the settings. The cover has provisions for a sealing "wire." The set-
tings are left to right, pickup current level for the time element, time dial, curve selection, frequency/reset time,
pickup current level for the instantaneous element, and the instantaneous element time delay. The settings are
all calibrated and are set by turning the rotary switch to the desired value. The switches are recessed, a small
screw driver is required to make the adjustment.
The relay may be supplied with one of three pointer styles as shown. The color is the color of the indicator, note
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the arrow location, all switches are shown in the 9:00 position.
Pointer styles
Yellow
Orange
White
Figure 4–1: DIAC 66K POINTER STYLES
The TOC pickup current is set directly in Amps with two rotary switches. An arrow is used to indicate setting
position. Setting the TOC or the IOC pickup current between, but not including 0 and a value less than mini-
mum 0.5 (5amp) or 0.1 (1Amp) will result in the relay defaulting to its minimum setting. Setting the TOC or IOC
pickup current to 0 will disable their respective elements. Although the time dial can be set to a value less than
minimum the relay will use the minimum setting.
4.3 ADJUSTMENTS: STANDARD INSTANTANEOUS UNIT
The standard instantaneous unit is an electromagnet that attracts a hinged armature when sufficient current is
applied. The armature carries a "T" shaped moving contact that bridges two stationary contacts when the coil is
energized. A target is displayed when the unit operated. Pressing the button in the lower left corner of the relay
cover resets the target.
The pickup range can be adjusted continuously over a four to one range by using the adjustable pole piece.
When the top of the core is lined up with the calibration stamping, an approximate value of pickup can be
determined. Dropout is about 40 to 50 percent of pickup.
Figure 2–19: IOC CURVE FOR THE STANDARD (EM) INSTANTANEOUS UNIT on page 2–20 shows the vari-
ation of operating time with applied current for this unit. Burden data of the standard unit is given the table
below.
GE Power Management
DIAC Type 66K Digital Overcurrent Relay
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