Installation and Wiring
1. Mount the relay on 35mm DIN rail in a suitable enclosure. Use one or two #12-30* solid or stranded copper or copper-clad aluminum con-
ductors —a terminal tightening torque of 7 in-lbs should be used.
2. Set the VOLTAGE LINE-LINE knob to the actual three-phase line-to-line voltage. The Voltage Line-Line knob on
the PMDU has two ranges (see right): 190-250V on the low voltage scale and 380-500V on the high voltage
scale. The unit auto senses the three-phase line-line voltage when applied and automatically selects one of
the two ranges. The PMD120 has a single adjustable range of 102-138V and the PMD575 has a single adjust-
able range of 460-600V.
3. Set initial settings on the UNDERVOLTAGE TRIP, TRIP DELAY and RESTART DELAY knobs to minimum. Set
initial setting on the UNBALANCE knob to maximum.
4. Connect the three-phase line-line voltage to terminals 1, 2 and 3 (see Wiring Diagram on the side of the relay
or on the back of this sheet). A connection to the neutral or ground is not required in Wye systems. DO NOT
connect output wires to terminals 7-12 until later (Step 12).
5. RESET: As standard, the PMD Series relays are in the Automatic Reset mode, which means they will
automatically reset once the fault has been corrected. However, they can be set up in the Manual Reset mode
by connecting an external N.C. switch across terminals 4 and 5. Upon application of three-phase voltage, the
PMD Series will go into Manual Reset mode if it recognizes a closure across terminals 4 and 5. After a fault
clears, the relay will not reset until the N.C. switch is opened. NOTE: When the unit is in the Manual Reset
mode, the N.C. switch must be opened after each Power-up to reset the relay and resume normal operation.
NOTE: This unit can only be set back to Automatic Reset mode from Manual Reset mode by removing three-phase voltage, removing the
N.C. switch across terminals 4 and 5, and reapplying the three-phase voltage.
6. Apply three-phase voltage. The LED indicator should initially flash GREEN if in theAutomatic Reset mode while the relay goes through its
start-up delay or waiting for an external switch to be operated if in the Manual Reset mode
and then illuminate solid GREEN. If the LED turns RED solid or flashing, a fault condition
exists and must be corrected. Use the LED Status Table at right or the Troubleshooting
Guide on back to determine exact cause of fault. Make required corrections.
Settings
7. REMOVE THREE-PHASE VOLTAGE for Steps 8-12.
8. Set the RESTART DELAY knob. This setting should be the time period required after a
fault has been cleared before the relay should automatically energize. NOTE: this value is
ignored when in the Manual Reset mode (see Step 5).
9. Set the UNDERVOLTAGE TRIP knob between 80 and 95% of the line-line voltage setting.
This value should be the same as the minimum operating voltage for the equipment to be
adequately protected.
10. Set the TRIP DELAY knob. This is the maximum time period that an unbalance, undervoltage or overvoltage condition should be allowed
to last. Too short a setting will cause nuisance tripping if there are momentary changes in the three-phase voltage. Too long a setting
could cause damage to the equipment. Note that the setting should be at least slightly longer than the time a three-phase motor is drawing
its inrush or startup current. This will avoid nuisance tripping caused by the starting current.
11. Set the UNBALANCE knob. This setting should be the maximum allowable unbalance in phase voltage that the three-phase system can
tolerate. Too low of a setting can cause nuisance tripping. Too high of a setting may not adequately protect the system.
* Use conductors rated for 75°C or better when used in ambient air temperatures exceeding 60°C.
(Continued on Back)
INSTALLATION
INSTRUCTIONS
PMD SERIES
THREE-PHASE MONITOR RELAY
901-0000-107
January 2018, Rev H (Replaces December 2017, Rev G) DANGER!
Potentially hazardous voltages are present. Electrical shock can cause death or serious injury.
Installation should be done by qualified personnel following all National, State & Local Codes.
BE SURE TO REMOVE ALL POWER SUPPLYING THIS EQUIPMENT BEFORE CONNECTING OR DISCONNECTING WIRING.
READ INSTRUCTIONS BEFORE INSTALLING OR OPERATING THIS DEVICE. KEEP FOR FUTURE REFERENCE.
IMPORTANT: READ THIS FIRST IF REPLACING A PMD SERIES PRODUCT WITH DATE CODE OF 1521 OR EARLIER
Macromatic made several product design enhancements on all PMD Series products manufactured with Date Code of 1522 or later (4th week of
May 2015).
These include a dial-in-dial line-line voltage scale on the PMDU with an increased 190-500V range, new LED fault codes & the ability to set the Line-Line Voltage
with power applied. Basic functionality and protection have been retained. For more information, please visit www.macromatic.com/new-pmd.
