Dwyer MPC User Manual

Page 12

LEAD/LAG OPERATION
The Mercoid

MPC pump controller is designed to easily operate a pair of pumps in the

most efficient manner possible. The controller has a 'lead/lag' feature that allows two
pumps to operate in an alternating fashion to minimize wear.

The Mercoid

MPC pump controller has a pair of set points each for pump 1 and pump 2. If

the lead/lag feature is turned off,

SP1H

and

SP1L

control pump 1 and

SP2H

and

SP2L

control

pump 2. If the lead/lag feature is turned on, pumps 1 and 2 will be controlled in the
alternating fashion described below. In all cases the P1 lamp will indicate activity of pump 1
and the P2 lamp will indicate activity of pump 2. The lead/lag operation is set in the Secure
menu with the item

LdL9.

Lead/Lag On
After installation, set the

SP1H

to the high level (pump on point) for standard operation. Set

SP1L

to the low level (pump off point). Set the

SP2H

to the level where you want BOTH

pumps to turn on (emergency pump on). Set the

SP2L

to the level where you want the

second pump to turn off (emergency pump off).

The controller will not allow you to set

SP1H

below

SP1L

above

SP1H

SP2H

below

SP2L

, or

SP2L

above

SP2H

. The controller will not allow you to set any set point or alarm

point above or below the programmed scale. No error messages are generated. The
displayed value will stop at an allowable point just above (or below, as the case may be)
the maximum or minimum allowed.

In normal operation, when the

SP1H

point is reached, one of the pumps will turn on. When

lead/lag is turned on, pumps 1 and 2 will alternate. If the level reaches the

SP2H

point, both

pumps will be turned on until the

SP2L

point is reached, where one of the pumps will turn

off. When

SP1L

is reached, remaining running pump will turn off. The last pump off will not

be the next pump on.

Lead/Lag Off
If lead/lag is turned off,

SP1H

and

SP1L

control pump 1 and

SP2H

and

SP2L

control pump 2.

There is no alternating function.

SEAL FAILURE OPERATION
The Mercoid

MPC Pump Controller is designed to work with most types of submersible

pump moisture sensors to detect outer seal failure. Most often the moisture sensor is a
conductance device that detects moisture in the oil chamber indicating an outer seal failure.
Using a 2.5 VDC power supply sent to the moisture sensor the MPC Pump Controller
monitors the resistance between the probe lead wires or the single probe lead wire and
ground. The resistance set point is adjustable over the range of 10K to 500K ohms
adjustable in 10K ohm steps, and is set with Secondary menu items

SFS1

and

SFS2

. When

the resistance of the moisture sensor decreases below the resistance set point the MPC
controller goes into the programmed seal failure mode.

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