41-251.21C
3
Type CRN-1
Reverse Power Relay
3.0 CHARACTERISTICS
The type CRN-1 relay is available with either a 120,
208, or 240 volt rating.
3.1
TIMER UNIT (T)
The timer unit is rated at 120, 208, or 240 volts, 60
hertz. The minimum operate value is 54% of rated
voltage. The continuous overvoltage capability is
110% of rated voltage. Characteristic time curves are
shown in figure 2 (page 8) for various voltages and
time dial settings.
3.2
DIRECTIONAL UNIT (D)
The directional unit has its maximum torque when
the current leads the voltage by 30°. The relay
should be connected using the 30° connection.
When using this connection the maximum torque of
the relay occurs at 100% P.F. The pickup value is .02
amp at rated voltage and maximum torque angle.
The pickup may be increased to .05 amp or higher by
increasing the spring tension.
3.3
TRIP CIRCUIT
The main contacts will safely close 30 amperes at
250 volts dc and the seal-in contacts of the indicating
contactor switch will safely carry this current long
enough to trip a circuit breaker.
3.4
TRIP CIRCUIT CONSTANT
4.0 SETTINGS
There is only one setting to be determined. This is
the time delay of the voltage operated timer, and it is
adjusted by the time dial position. Figure 2 gives a
curve of time delay vs. time dial setting for various
impressed voltages. Time is approximately propor-
tional to time dial setting.
4.1
INDICATING CONTACTOR SWITCH (ICS)
There are no settings to make on the indicating con-
tactor switch (ICS).
5.0 INSTALLATION
The relays should be mounted on switchboard pan-
els or their equivalent in a location free from dirt,
moisture, excessive vibration and heat. Mount the
relay vertically by means of the four mounting holes
on the flange for the semi-flush type FT case. Either
the stud or the mounting screws may be utilized for
grounding the relay. External toothed washers are
provided for use in the locations shown on the outline
and drilling plan to facilitate making a good electrical
connection between the relay case, its mounting
screws or studs, and the relay panels. Ground wires
may be affixed to the mounting screws or studs as
required for poorly grounded or insulating panels.
Other electrical connections may be made directly to
the terminals by means of screws for steel panel
mounting or to the terminal stud furnished with the
relay for thick panel mounting. The terminal stud may
be easily removed or inserted by locking two nuts on
the stud and then turning the proper nut with a
wrench.
For detail information on the FT case refer to I.L. 41-
076.
For correct operation, the type CRN-1 relay should
be connected so that maximum torque occurs for
unity power factor on the system. Since the direc-
tional unit has a 30° characteristic, this may be
accomplished by using the connections shown in fig-
ure 3 (page 9).
The voltage operated timer unit should be connected
across the line. External schematic for this applica-
tion as shown in figure 3 (page 9).
6.0 ADJUSTMENTS AND
MAINTENANCE
The proper adjustments to insure correct operation of
this relay have been made at the factory and should
not be disturbed after receipt by the customer. If the
adjustments have been changed, the relay taken
apart for repairs, or if it is desired to check the adjust-
Indicating Contactor Switch (ICS)
Ampere Pickup
Ohms dc Resistance
0.2
1.0
2.0
8.5
0.37
0.10